Case number (serial number) on warranty card

Hi, my brother has recently bought an Aquatimer (the older model IW3568) new from an AD but the case/serial number on the IWC Warranty Card (the number printed below the barcode) doesn't match the watch serial number. However, on the warranty card for his previous IWC watch (another Aquatimer) purchased a few years ago from the same AD, the case number printed under the bar code did match the watch's serial number. Also, on the card for the new watch, the AD has hand-written the case number in pen.

My brother's wondering if the shop has at some point in the past mixed up the cards for two different watches (of the same model number), and he is still waiting to speak to the manager about it. But I thought in the meantime I could ask on this very helpful forum, does it really matter that the case number printed on the card doesn't match the watch's serial number, just as long as the hand written number is correct? Or should he insist that they give him a new warranty card? Is it even possible for the dealer to request one from IWC with a particular serial number printed on it??

Or should he just not worry about it?

Thanks

Had the same issue witha JLC Reverso for her ladyship. Correct card box and papers were found and exchanged. What happened to the incorrect cards and box I have no idea at the authorised dealer.
Papers and cards are important as they refer to an exact watch, they are not vague "open" guarantee cards to the best of my knowledge. An open guarantee card would be open to abuse and fraudulent misuse and no doubt they would be copied.

Thank you Gregg. I'll post back for info if/when my brother gets an answer about this.