I think wedding/bridal showers are very personal things. I think everyone person has to do some deep introspection and figure out what works best for them. I can't tell you what will work best for your friends/colleagues, but I can tell you what makes sense for me, and you can take it from there.
First of all, I think parties are fun. I am always on the lookout for opportunities to get together with people for some merriment. I think it's awesome that you have a colleague who wants to throw a party for you, as well as personal friends who might also want to throw one.
I don't think it's "weird for folks to be invited to multiple showers for the same person," but I think it's important to explain to your friends that a gift is not required/expected. I think we should all be very careful about the financial strain that our weddings place on others. Weddings (and the celebrations leading up to them) should focus more on community, connection, and fun and less on material goods.
I'm curious to know what others think!