In Windows LR 11.5 Japanese (ja_JP), Ctrl + Y is assigned to both Create Virtual Copy and Redo:
"$$$/AgLibrary/Menu/Shared/CreateVirtualCopies/Key=Cmd+y"
"$$$/Application/Menu/Edit/RedoWin/Key=Cmd+y"
When the Redo command isn't greyed out, Ctrl + Y invokes Redo, otherwise it invokes Create Virtual Copy.