Bridges can be hit or miss. Grab 2 or 3, see if they work. If not, grab a few more. Once you find a few that work, definitely stick with them. Don't change them. It's for your safety. You don't want to rotate your entry points often. They may be taken offline eventually and you'll have to get more, it's the nature of the Tor network. Relays/bridges exist because of volunteers who may quit at some point. Just stick with the useful ones for as long as possible. I don't know why so many people ask this question. Yes of course it's safe. What happens on one computer has no effect on what happens on the other computer. No problem man.