Of course. Which is why redundancy is so vitally important (I should have made that point above).The very first thing you need to get out of your head if you plan to dive solo is that someone might help you. You're 100% on your own and if you get it wrong you'll just have to do the decent thing and drown. Try not to drift off and make it hard on searchers.
Diving alone on a lake with no other divers needs to be done with proper redundancy. Sidemount, rebreather+bailout, or twinset. Oh, or a single + pony.