If I run multiple businesses from my home office do I just deduct it once for any of the businesses?

how do i enter multiple bussiness

No, you can enter a Home Office for each business, assuming the other qualifications are met. 

The only caveat is that if you use the same office for multiple businesses, you can't deduct the office expenses multiple times; you have to split them between the businesses.

For more information:

https://ttlc.intuit.com/replies/4773265