Accessing two Shopify accounts on one POS hardware terminal

DB9
Tourist
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Hi, I have two businesses both located in one retail space. I want to set up a Shopify account/website for each business and be able to checkout customers for either business on the same POS hardware terminal. After lengthy discussions with multiple Shopify tech support staff, for some reason this is impossible so I'll be forced to purchase two POS hardware terminals (+ iPads) that will sit side by side on my checkout desk. If the POS software was web based, I'd just have two browser tabs open and flip back and forth, but I assume it's an app. I just thought I'd ask if any brilliant entrepreneurs out there have figured out a way to do this. Thanks in advance!