I asked our SM about this and he said,
"that is subject to interpretation, I consider one who comes up to the register as one customer. when you or anyone comes back for another transaction, you are considered another customer. and that is also how the register views it.
I don't feel like a criminal because if something isn't clear, I ask the manager, not any Tom, Dick or Harry at the store. It doesn't hurt to ask, its better to be well informed rather than just guessing or being embarrassed by store personnel and treated like a thief.