I agree with @Nanren888: 'a couple of shoes' is not a normal expression. We don't say 'a couple of shoes'. The only time you might come across this is if they were probably two objects which did not belong together. For example:
"The foxes in our neighbourhood are always leaving random objects around. Just look at what's in the garden this morning: there's half a Barbie doll, an empty tortilla chips packet, a chewed-up wallet and a couple of shoes".
In this context, we know that these are likely to be two random shoes - maybe a child's sandal and a man's trainer.
Two shoes of the same pair would only be called 'a couple' (meaning two) if it really didn't matter that they were a pair. Maybe all the family's shoes are stacked up on a shoe rack, and you grab two shoes without looking to throw at someone in a fight. These might be a pair or they might not be a pair - the point is that that these are two random shoes picked up by chance.
However, if the key point is that the shoes are the left and right of the same pair, a native English speaker would never say 'a couple'. We would never say, for example, that someone is wearing a couple of new shoes. Two shoes, a left and a right, which are manufactured, bought and worn together, are always referred to as 'a pair of shoes'.
I hope that's clear now.