My wife is in one checkout line and I'm going to get in a second one.
What is your reasoning for doing that?
I just want to get out of this place as quickly as possible.
Just make sure you are not causing the queue to be longer. There is no rules against that, so do as you please.
It's my wife so I don't see why that would be a big deal.
I agree, it's a non-issue and ultimately a purchase is going to be made and you're not slowing down the process. Checking out can be such a hassle. I hope the line moves quickly for you!