Error Oracle redwood UI "the re-assign to person and requisition preparer cannot be the same person"

One of my user is facing one issue with requisition reassignment and Issue she explained is,
She has multiple lines within 1 requisition and from classic Requisition UI she was able to reassign Line 1 to USER1 (eg.David) and now when she is trying to reassign the rest of the lines to USER1 again(David) from redwood application , "She is getting this error message-> the re-assign to person and requisition preparer cannot be the same person"

And earlier from classic UI she was able to perform this functionality line wise.