Would it be possible to add this as an option in the extension? See below:
"I edited res/ext.SimpleBatchUpload.js around line 54 to include this new parameter ("sequentialUploads: true,": ... dropZone: $( '.fileupload-dropzone', container $ sequentialUploads: true, progressInterval: 100,"
See: https://github.com/ProfessionalWiki/SimpleBatchUpload/issues/25