TN transfer to new company

I am working for company 'A' till the end of July and I have accepted a new job with company 'B' where I will be starting from August 1. I have some vacation time accumulated but I cannot take the days off now because of the time sensitive stuff I am working on. My question is if I work till the end of July with Company 'A' and start with company 'B' on August 1. Can I make my resignation with company 'A' effective September 1? I ask because I cannot cash my vacation. Will this violate anything in my TN status because technically I will be working with two companies for about a month and getting paid from two places?

You can have multiple TN-1s. Not a wise move to actually stop working with a gap, because if you've been in the US for more than six months they won't let you back in as a visitor.