Multiple flag fix (#1742)

* fix

* multiple file logic cleanup

* fix

---------

Co-authored-by: a <a>

src/main/resources/templates/merge-pdfs.html

@@ -20,7 +20,7 @@
               <form action="api/v1/general/merge-pdfs" method="post" enctype="multipart/form-data">
                 <div class="mb-3">
                   <label th:text="#{multiPdfDropPrompt}" for="fileInput-input"></label>
-                  <div th:replace="~{fragments/common :: fileSelector(name='fileInput', multiple=true, accept='application/pdf')}"></div>
+                  <div th:replace="~{fragments/common :: fileSelector(name='fileInput', multipleInputsForSingleRequest=true, accept='application/pdf')}"></div>
                 </div>
                 <div class="mb-3">
                   <input type="checkbox" name="removeCertSign" id="removeCertSign">