Hello, this is a really silly question but I recently purchased a BMW 1 Series which came with two keyfobs. The original key is working fine, but the spare didn't have a working battery after I replaced the battery it still isn't working. I think decided to open up both keyfobs and compare the physical keys and the pattern on the two keys is different, and the spare keyfob physical key doesn't unlock the car. Does anyone know what could have happened here, was the spare key lost by the owner and he purchased another one?

The remote may just need resetting to the car. It’s easy to do and there are loads of tutorials on the net. Just google key fob ews programming. 
hopefully it starts the car…. That’s the hard part. 

Morning Velin

Welcome to the Forum

If the key blade is a different pattern and doesn't work then it's highly possible that either the previous owner brought a cheap replacement just to sell with 2 keys. Or he had 2x1 series cars and now has another keyset just like yours 😅

As Stu says try re-programming the Fob that may work the final solution is BMW for another key £££. As an aside my E53 (2003) is still operating on the original OEM keys both work, my E70 (2009) has had 2 battery changes

Dave

Thanks both of you for your help! I will give re-programming a go and then I guess it will either be a matter of contacting the seller or purchasing another key from BMW which will cost me an arm and a leg 😅

I gave it a go at re-programming it and I get "Unidentified remote control key" at the moment 😞

That is definitely not the key for that car then, I would guess that someone has mixed up 2 sets of keys

I would guess your BMW Dealer would charge about £150 (that is a guess) so check with them, at least you have a working key so can use the car while saving your hard earned cash. That is unless the seller says woops and has the other.

Good Luck

Dave