I am a model with a modelling agency, can I register at this website too?

Yes you can. bodyNsoulModels.com is NOT a modelling agency and as such does not compete with the agency you are affiliated with. It is a network website. You get to know photographers, makeup artists, hairstylists and hopefully you get to make some beautiful pictures with those people that can improve your portfolio. Many of them will work for their portfolio on TFP basis with the models and each other.

The website also lists casting calls, those can be for TFP or commercial projects. If you are with a modeling agency it is very important to consult with them, or refer to them when you are considering or negotiating your participation in a commercial project. That is what you have them for, to protect your interests.