My oldest did this too, it was a phase. If it works for you to get more sleep, don't worry about it. To avoid waking you up, you could even make a little bed for her next to yours and just tell her to crawl in there without waking you, or have her start her night there. Or let husband get a good night's rest in the guest room so he can go to work, and then you can go to bed when the 2 year old does with the baby in a bassinet, so you are all 3 in the same room. Pretty soon the 2 year old will realize that waking every 2 hours to a crying baby is no fun, and will probably go back to her own bed.
When there is a new baby, you just do what works for you. Or can hubby deal with the 2 year old and leave you sleeping? There are families that share a big bed until kids are quite large, so "normal" runs from strict sleeping alone in one's own bed from day 1 all the way to sleeping with mom and dad to the age where I think it sounds a little creepy (think of 2 queen sized beds next to each other with mom, dad and 2 kids in it until teen years - but it works for them).
If the nap time is allowing you some rest during the day, try to nap then too. I know it is hard to do, you can quickly throw in a load of wash or do some dishes, but they can wait. At this stage mom should nap when she can! Congratulations on your new little baby, and I hope you recover soon with much needed rest.