diff --git a/src/org/labkey/test/tests/SampleTypeParentColumnTest.java b/src/org/labkey/test/tests/SampleTypeParentColumnTest.java
index 3cb68c6e6a..402129f106 100644
--- a/src/org/labkey/test/tests/SampleTypeParentColumnTest.java
+++ b/src/org/labkey/test/tests/SampleTypeParentColumnTest.java
@@ -27,6 +27,7 @@
 import org.labkey.test.BaseWebDriverTest;
 import org.labkey.test.Locator;
 import org.labkey.test.categories.Daily;
+import org.labkey.test.components.domain.DomainFieldRow;
 import org.labkey.test.components.ui.domainproperties.samples.SampleTypeDesigner;
 import org.labkey.test.pages.ImportDataPage;
 import org.labkey.test.pages.experiment.CreateSampleTypePage;
@@ -699,8 +700,6 @@ public void testAliasNameConflictsWithFieldName()
         goToProjectHome();
         projectMenu().navigateToFolder(PROJECT_NAME, SUB_FOLDER_NAME);
 
-        String path = PROJECT_NAME + "/" + SUB_FOLDER_NAME;
-
         List<FieldDefinition> fields = new ArrayList<>();
 
         fields.add(new FieldDefinition(ALIAS_NAME_CONFLICT, FieldDefinition.ColumnType.String));
@@ -726,7 +725,7 @@ public void testAliasNameConflictsWithFieldName()
                 String.join("\n", errors));
         updatePage.removeParentAlias(0);
 
-        log("Now add a valid parent column and check that you cannot now add a field in the sample type with the same name.");
+        log("Now add a valid parent column and check that you cannot add a field in the sample type with the same name.");
         updatePage.addParentAlias(GOOD_PARENT_NAME, SampleTypeDesigner.CURRENT_SAMPLE_TYPE);
         updatePage.clickSave();
 
@@ -751,7 +750,38 @@ public void testAliasNameConflictsWithFieldName()
 
         updatePage.clickCancel();
 
-        log("Validated name conflicts.");
+        // GH Issue 1257
+        clickFolder(SUB_FOLDER_NAME);
+        log("Check that you cannot add a field with an import alias that conflicts with the parent import alias");
+        updatePage = sampleHelper.goToEditSampleType(SAMPLE_TYPE_NAME);
+        DomainFieldRow fieldRow = updatePage.getFieldsPanel().addField("DupeAliasCheck");
+        fieldRow.setImportAliases(GOOD_PARENT_NAME);
+        errors = updatePage.clickSaveExpectingErrors();
+        errorMsgExpectedTxt = "Field 'DupeAliasCheck' has an import alias '" + GOOD_PARENT_NAME + "' that conflicts with a parent alias header.";
+        assertThat("Error message", String.join("\n", errors), CoreMatchers.containsString(errorMsgExpectedTxt));
+
+        log("Check that you cannot add a parent import alias that conflicts with a field alias");
+        String fieldAlias1 = "Alias1";
+        String fieldAlias2 = "Alias2";
+        fieldRow.setImportAliases(fieldAlias1 + " " + fieldAlias2);
+        updatePage.removeParentAlias(GOOD_PARENT_NAME);
+        updatePage.addParentAlias(fieldAlias2);
+        errors = updatePage.clickSaveExpectingErrors();
+        errorMsgExpectedTxt = "Field 'DupeAliasCheck' has an import alias '" + fieldAlias2 + "' that conflicts with a parent alias header.";
+        assertThat("Error message", String.join("\n", errors), CoreMatchers.containsString(errorMsgExpectedTxt));
+        updatePage.removeParentAlias(fieldAlias2);
+        log("Save with the import aliases defined for a field.");
+        updatePage.clickSave();
+
+        log("Verify an update to add a conflicting alias for an existing field alias also fails");
+        clickFolder(SUB_FOLDER_NAME);
+        updatePage = sampleHelper.goToEditSampleType(SAMPLE_TYPE_NAME);
+        updatePage.addParentAlias(fieldAlias1);
+        errors = updatePage.clickSaveExpectingErrors();
+        errorMsgExpectedTxt = "Field 'DupeAliasCheck' has an import alias '" + fieldAlias1 + "' that conflicts with a parent alias header.";
+        assertThat("Error message", String.join("\n", errors), CoreMatchers.containsString(errorMsgExpectedTxt));
+
+        updatePage.clickCancel();
     }
 
     @Test
diff --git a/src/org/labkey/test/tests/SampleTypeTest.java b/src/org/labkey/test/tests/SampleTypeTest.java
index 8e01befc55..79f6264e96 100644
--- a/src/org/labkey/test/tests/SampleTypeTest.java
+++ b/src/org/labkey/test/tests/SampleTypeTest.java
@@ -301,7 +301,69 @@ public void testCustomProperties()
         assertTextPresent(stringCol1.getLabel(), stringCol2.getLabel(), stringCol3.getLabel(), calcCol.getLabel(), "PlainValue", "PercentValue", "PlainValueConcat");
     }
 
-        // Issue 47280: LKSM: Trailing/Leading whitespace in Source name won't resolve when deriving samples
+    @Test  // GH Issue 1257
+    public void testOverlappingAliases()
+    {
+        final String sampleTypeName = "OverlappingAliasSampleType";
+        final String fieldOne = "AliasFieldOne";
+        final String fieldTwo = "AliasFieldTwo";
+        final String sharedAlias = "sharedAlias";
+
+        SampleTypeHelper sampleHelper = new SampleTypeHelper(this);
+
+        clickProject(PROJECT_NAME);
+        CreateSampleTypePage createPage = sampleHelper
+                .goToCreateNewSampleType()
+                .setName(sampleTypeName);
+        DomainFormPanel fieldsPanel = createPage.getFieldsPanel();
+
+        log("Verify there can be no duplicate import aliases for different fields in a sample type (case-insensitive). ");
+        fieldsPanel.addField(fieldOne).setImportAliases(sharedAlias);
+        fieldsPanel.addField(fieldTwo).setImportAliases(sharedAlias);
+
+        checker().verifyThat("Expected an error when two fields share an import alias",
+                String.join("\n", createPage.clickSaveExpectingErrors()),
+                containsString("You have 2 field errors."));
+        checker().screenShotIfNewError("duplicateImportAlias");
+
+        log("Aliases differing only by case are still duplicates.");
+        createPage = new CreateSampleTypePage(this.getDriver());
+        fieldsPanel.getField(fieldTwo).setImportAliases(sharedAlias.toUpperCase());
+        checker().verifyThat("Expected an error when two fields share an import alias differing only by case",
+                String.join("\n", createPage.clickSaveExpectingErrors()),
+                containsString("You have 2 field errors."));
+        checker().screenShotIfNewError("duplicateImportAliasIgnoringCase");
+
+        log("Verify there can be no import aliases that collide with field names (case-insensitive).");
+        createPage = new CreateSampleTypePage(this.getDriver());
+        fieldsPanel.getField(fieldTwo).setImportAliases("");
+        fieldsPanel.getField(fieldOne).setImportAliases(fieldTwo);
+        checker().verifyThat("Expected an error when an import alias matches another field's name",
+                String.join("\n", createPage.clickSaveExpectingErrors()),
+                containsString("Import alias '" + fieldTwo + "' on field '" + fieldOne + "' conflicts with a field name."));
+        checker().screenShotIfNewError("importAliasConflictsWithFieldName");
+
+        log("An alias that matches a field name except for case is still a conflict.");
+        createPage = new CreateSampleTypePage(this.getDriver());
+        fieldsPanel.getField(fieldOne).setImportAliases(fieldTwo.toLowerCase());
+        checker().verifyThat("Expected an error when an import alias matches another field's name except for case",
+                String.join("\n", createPage.clickSaveExpectingErrors()),
+                containsString("Import alias '" + fieldTwo.toLowerCase() + "' on field '" + fieldOne + "' conflicts with a field name."));
+        checker().screenShotIfNewError("importAliasConflictsWithFieldNameIgnoringCase");
+
+        log("An alias that repeats its own field's name is redundant but not ambiguous, so it should be allowed.");
+        fieldsPanel.getField(fieldOne).setImportAliases(fieldOne);
+        createPage.clickSave();
+
+        clickProject(PROJECT_NAME);
+        UpdateSampleTypePage updatePage = sampleHelper.goToEditSampleType(sampleTypeName);
+        checker().verifyEquals("Import alias matching its own field name was not saved",
+                fieldOne, updatePage.getFieldsPanel().getField(fieldOne).getImportAliases());
+        checker().screenShotIfNewError("selfReferencingImportAlias");
+        updatePage.clickCancel();
+    }
+
+    // Issue 47280: LKSM: Trailing/Leading whitespace in Source name won't resolve when deriving samples
     @Test
     public void testImportSamplesWithTrailingSpace() throws IOException, CommandException
     {