It is not smart to work on multiple websites at once when you are starting out. However, it is also not smart to stick with a niche you have little interest in. It would probably be smart to switch now and not waste time on a site you will just drop later on.

Unless of course you are just in a slump right now and think you will change your mind again later. I see so many people feel they are in the wrong niche but are afraid to switch. If and when they finally do switch they wish they had done it sooner. It is much easier to be more consistent and productive in a niche you are interested in and feel driven to learn about or share.

I know someone here who picked a niche and quickly realized she should be in something else. She heard the advice not to start a second site and decided to stay with the first one at least through the training lessons. After she finished the training she switched. She wishes she had switched in the beginning.