UC Authorizenet Multi is an Ubercart module that allows users to add multiple payment gateways (only authorize.net accounts) to their site and select which gateway should be associated with a product node. During checkout, the appropriate gateways are charged.
This was originally developed for a political advocacy organization (C4) that collects donations for candidates and for the C4 itself. For legal purposes, donations for candidates must be deposited into a separate bank account than the C4. This module allows them to create "products" (ie. donations) that, during checkout, are deposited into either the C4 bank account or the candidate bank account. The module supports an unlimited number of authorize.net accounts.
Note: The module currently does not work with line items, such as taxes, and will mostly likely fail and eat baby kittens if you have an Ubercart module installed that uses them.