Tax LLM programs will care most about grades in Tax classes, not LLM classes in global basketweaving law or anything else.
I'm not even sure if it's possible to get another LLM if you've already got one. Check with the schools. Even if they let you do it, why on earth would you think it would be a good idea? I hope you aren't planning to take out loans for it.
Let me guess, you did an LLM and it didn't help you get a job and now you think by doing a tax LLM from a top school will help break you into some kind of high paying job?
I'm afraid that isn't likely. Even tax LLMs from the top schools have been having a hard time finding jobs for the last few years. Even JD grads from top schools who came out in the last couple years are having a hard time finding any decent work.