Each fresh pack I open gets a letter, and then a number. The letter is the batch, and the number identifies which pair it is....
A1, B3,... Etc...
Then if only one sock in a pair gets a hole, then I can wait until another one from that same batch gets a hole in it and then mate the two "orphans" to each other...
Kinda like rotating your tires to keep the wear even. This keeps the socks with even wear together....