Fix #17892 Duplicate Due column in Card Browser

- Added Unit test for Fix #17892 Duplicate Due column in Card Browser

Author: dorrin-sot

AnkiDroid/src/main/java/com/ichi2/anki/browser/BrowserColumnCollection.kt

@@ -66,7 +66,9 @@ class BrowserColumnCollection(
                     val value = mode.defaultColumns()
                     value.split(SEPARATOR_CHAR).map { CardBrowserColumn.fromColumnKey(it) }
                 }
-            return BrowserColumnCollection(columns)
+            // shared preferences had duplicate columns for unknown reasons
+            // this removes duplicates on load, any saves will be de-duplicated
+            return BrowserColumnCollection(columns.distinct())
         }
 
         class ColumnReplacement(

AnkiDroid/src/test/java/com/ichi2/anki/CardBrowserTest.kt

@@ -1153,6 +1153,27 @@ class CardBrowserTest : RobolectricTest() {
         assertThat("column 2 reset to default", cardBrowser.columnHeadings[1], equalTo("Card Type"))
     }
 
+    @Test
+    fun `loading duplicate columns returns distinct`() {
+        // GIVEN: Shared preferences exists for display column selections
+        // with duplicate values
+        getSharedPrefs().edit {
+            putString(BrowserConfig.ACTIVE_CARD_COLUMNS_KEY, "question|cardDue|cardDue|deck")
+        }
+
+        // WHEN: CardBrowser is created
+        val cardBrowser: CardBrowser = getBrowserWithNotes(7)
+
+        // THEN: CardBrowser only shows distinct columns.
+        for ((i, column) in listOf("Question", "Due", "Deck").withIndex()) {
+            assertThat(
+                "column ${i + 1} reset to default",
+                cardBrowser.columnHeadings[i],
+                equalTo(column),
+            )
+        }
+    }
+
     @Test
     @Ignore("issues with launchCollectionInLifecycleScope")
     fun `column titles update when moving to notes mode`() =