I got given some baby clothes second hand, some I bought new, some I bought second hand, and some were given new as gifts.
I would not have been able to distinguish them except for the odd new purchase that was not too badly worn when I came to pass it down to DC2 or sell it on.
What do other people do - label all their baby clothes with the giver's name? If you didn't do that, how did you know where they came from?
pictish that's another alternative I suppose!
OP a sofa is totally different. You can tell that one sofa came from one owner. I can't for the life of me tell which baby items came from which source. Do I have to ask about the new gifts as well? Do I have to ask before using them for DC2?
If someone had said they wanted to loan us a cot/buggy/high chair then that's fine as long as they weren't expecting it back in useable condition (actually the cot is fine, the buggy went to the landfill ages ago, and the high chair is fine but a bit scratched). I can lay my hands on those at a moment's notice.
Possibly the same is true of one gorgeous and pristine baby outfit e.g. for a christening.
But if someone gave me a large bundle of baby clothes and said they wanted them back I'd just not take them. I can't realistically say I'll be able to work out which they were after 6 months of waiting to wear them and then 6 months of wearing them, let alone after 2 DC.