Add check if text watcher is already running

payments-core/src/main/java/com/stripe/android/view/StripeEditText.kt

@@ -115,6 +115,12 @@ open class StripeEditText @JvmOverloads constructor(
     val internalFocusChangeListeners = mutableListOf<OnFocusChangeListener>()
     private var externalFocusChangeListener: OnFocusChangeListener? = null
 
+    private val isLastKeyDeleteTextWatcher = object : StripeTextWatcher() {
+        override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
+            isLastKeyDelete = count == 0
+        }
+    }
+
     protected open val accessibilityText: String? = null
 
     override fun setTextColor(colors: ColorStateList?) {
@@ -199,14 +205,10 @@ open class StripeEditText @JvmOverloads constructor(
         // On some devices, the OnKeyListener isn't invoked for software keyboards. It is invoked on
         // other devices such as my Pixel. To fix the issue for all devices, we're adding an
         // additional text watcher to keep isLastKeyDelete in the correct state.
-        val textWatcher = object : StripeTextWatcher() {
-            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
-                isLastKeyDelete = count == 0
-            }
+        if (isLastKeyDeleteTextWatcher !in textWatchers.orEmpty()) {
+            addTextChangedListener(isLastKeyDeleteTextWatcher)
         }
 
-        addTextChangedListener(textWatcher)
-
         // This method works for hard keyboards and older phones.
         setOnKeyListener { _, keyCode, event ->
             isLastKeyDelete = isDeleteKey(keyCode, event)