diff --git a/src/components/key-value-form/key-value-convert.test.ts b/src/components/key-value-form/key-value-convert.test.ts
index 7a81c6cdea..36edb14101 100644
--- a/src/components/key-value-form/key-value-convert.test.ts
+++ b/src/components/key-value-form/key-value-convert.test.ts
@@ -66,4 +66,17 @@ describe("Tests the convert functions for attribute input", () => {
       { key: "", value: "" },
     ]);
   });
+
+  it("convert duplicates into array values", () => {
+    const given = [
+      { key: "theKey", value: "one" },
+      { key: "theKey", value: "two" },
+    ];
+
+    //when
+    const result = keyValueToArray(given);
+
+    //then
+    expect(result).toEqual({ theKey: ["one", "two"] });
+  });
 });
diff --git a/src/components/key-value-form/key-value-convert.ts b/src/components/key-value-form/key-value-convert.ts
index abb7c916e4..1e8437dd65 100644
--- a/src/components/key-value-form/key-value-convert.ts
+++ b/src/components/key-value-form/key-value-convert.ts
@@ -1,20 +1,24 @@
 export type KeyValueType = { key: string; value: string };
 
-export const keyValueToArray = (
-  attributeArray: KeyValueType[] = []
-): Record<string, string[]> =>
-  Object.fromEntries(
-    attributeArray
-      .filter(({ key }) => key !== "")
-      .map(({ key, value }) => [key, [value]])
-  );
+export function keyValueToArray(attributeArray: KeyValueType[] = []) {
+  const validAttributes = attributeArray.filter(({ key }) => key !== "");
+  const result: Record<string, string[]> = {};
 
-export const arrayToKeyValue = (
-  attributes: Record<string, string[]> = {}
-): KeyValueType[] => {
+  for (const { key, value } of validAttributes) {
+    if (key in result) {
+      result[key].push(value);
+    } else {
+      result[key] = [value];
+    }
+  }
+
+  return result;
+}
+
+export function arrayToKeyValue(attributes: Record<string, string[]> = {}) {
   const result = Object.entries(attributes).flatMap(([key, value]) =>
     value.map<KeyValueType>((value) => ({ key, value }))
   );
 
   return result.concat({ key: "", value: "" });
-};
+}