Issue #2884052 by zviryatko, Krzysztof Domański, alexpott, drclaw, vijaycs85, Madis, charlotte.b, mcdruid, Berdir, lauriii: Uploading a managed file on a custom form that allows multiple files also triggers the remove button which results in a duplicate temporary record and results in the file being deleted

SA-CORE-2016-005 by larowlan, xjm, David_Rothstein, Dave Reid, Crell, cilefen, alexpott, mlhess, catch, pwolanin, YesCT, dawehner, quicksketch, Heine, znerol, charlotte.b, jnicola, ezraw

(cherry picked from commit c5da97f9)