I am a home health aide and I work for a w2 company, but I also work for a 1099 company. Can I claim a mileage deduction when I drive from my 1099 Client to my W2 client on the same day?

Yes, from a regular job to a second job is deductible.

So how much time inbetween is ok.  Can you have lunch then go to your next job and still deduct miles?

If the client is in the same location every day and that is your only client, the mileage might be considered commuting and as such would not be deductible.

I have one client all week, but one day a week I have 2.  So, when I go from my regular client (client #1) to my one day a week client (client #2), I think that is deductible.  But, do I have to go immediately to the 2nd client, or can I stop for lunch if it is on the way and then go to the second client and deduct those miles from Client #1 to Client #2?  What is the time frame to get to the other client?