Nothing to stop you but is it worth it? If, for example, there was an incident, or heaven forbid, an accident all relevant paperwork would be examined. For the sake of a few hours in your logbook you could jeopardise your long-term career aspiration or goal. Finally, some degree of integrity is implicit in this system. Can you imagine pitching up at an airline or flying club claiming more experience than you really have? The consequences are at best embarrassing but, at worst, dangerous.
Seem to remember chap "Parker-penned" his logbook to get an airline job. By all accounts, he was pretty good. Got found out eventually and, guess what, he lost his licence and job.
What are you building hours towards?