They can be but it would be counter-intuitive. Redo is the antonym for undo and should only be enabled when the last command was an undo, which should automatically disable the repeat command. Redo remains enabled until the undo history is empty, or another command besides undo is selected, at which point the repeat command should be enabled again.
undo
You use redo to undo an undo, but you use repeat to initiate the same keystrokes just completed in your typing.
Repeat the cheat.
cut
redo means do something over again and undo means to do it back
Click UNDO three times.
quick access toolbar
CRTL + Y is a shortcut for repeat typing or redo. Usually, the repeat typing button is near the undo button.
Although Ctrl + Z will undo most all commands before you save a file, if you accidentally undo too much you can always use Ctrl+Y to redo the undos in reverse order.
Undo (Ctrl-Z) - Undoes the last comment undertaken i.e Delete a word , click UNDO the word is printed back to its position. Redo - (Ctrl-Y) Redoes the command again in this example deletes the word again
Commands that are not relevant at a particular time will be greyed out. For example, before you do a Paste, you must first have done a Copy or a Cut. If you haven't done either of those, then Paste will be greyed out. Once you Copy or Cut something, then Paste will become black and you can use it. If you have not done anything, then you cannot do an Undo, so it is greyed out. Redo will be greyed out until you have done an Undo. The same applies to many other commands. So commands will be grey or black, depending on what else you have done.