ATX and Taxwise are the same company, Universal Tax Systems. ATX and Taxwise are product names, not companies. Both were purchased by CCH - Wolters Kluwer last year. Some duplicated services have been merged (customer support, sales, shipping, HR) but the core product areas are still separate with the Taxwise product line primarily in Georgia, ATX in Maine & Florida.
It's taking a little while for Tech Support to figure out their secret identities and stop answering the phones as Clark Kent. :)