Go on the interview. There is no harm in talking to anyone. Now, if they offer you a job, that is another question.
You then need to figure out the long term implications. For instance, if Job A is with a company that is part of many others, and you want to be working in them in the future, money isnt always the answer, but long term is.
If Job B is something you want to be doing in the future, and Job A won't cause you harm by not taking it after you have accepted, then do it.
As an employer, I would rather have someone tell me they don't want to start working than work for us for a month, and then quit. That is ONE month of training, teaching and investment I could of used on someone else that really wanted to work in this day and age.