My kids are 21 months apart, and it was a BIG adjustment for us all to get used to. So I feel for you! Perhaps nothing has changed in your daughter's bedtime routine, but if you think about the big picture, everything has changed for her.
When our daughter was born, our son went from being the center of attention, to having to share mom and dad's attention with a very demanding newborn--all through the day. What I needed to do (and it was hard with the demands of a newborn) was deliberately give him attention and special time with him during the day. This really helped with behavior overall. For example, when it was time to nurse the baby, instead of retreating to the bedroom, I let my son sit on the couch right beside me and we'd watch a bit of a favorite show together while the baby nursed. It might be that your daughter is missing her special attention, and it's showing up in her acting out at bedtime. If you are able to give her more special time during the day, it might help all around.
Also, it's probably going to take her more than 2 weeks to really get used to having the new tiny person in the house (and in her room). You might need to change her bedtime routine a little during the adjustment period. Perhaps when it's tuck-in time for your toddler, it could also be bedtime feeding for the baby? If you have a chair or rocker in the girls' room, you could feed the baby in the dim light while your toddler is falling asleep. It would help her feel near to you, but she would have to understand that she must stay in bed quietly or it would disturb the baby and you would have to leave the room. Because this arrangement is connected to the baby's feeding, you don't have to worry about keeping it up forever.
Hope you find something that helps!