Two Master's Degrees? Is it worth it?

So I am currently working on my Ms in Museum Studies and I would really like to work in conservation of museum materials, which I get to do to a degree in my current program, but I would like to get to do more of. Conservation of museum and archaeological materials mostly exist, in the US anyway, as MA or MS degrees not as a PhD( that I have found anyway).

Would it be worth it to go back and get a second master’s in conservation later on, or should I just take as many outside courses in conservation as possible so that I have the training even though I might not use it all the time? I have heard that having two Masters looks like you are over qualified or a failed PhD candidate.

Thank you for the help and any advice!

I would only go back and get a second master’s degree if I needed it to do a specific kind of job or enter a career, and it would have to be significantly different from the first one. So I can’t see any reason to do one in museum studies and then another in conservation of materials. I would just take the extra coursework.