I'm not entirely sure to be honest. Hopefully someone comes across this who has purchased a 1:1 rep Imprime belt and can post their serial number for you to compare to yours. But like said with the link you provided above of your seller, he's selling Gucci belts for $180 which is really suspect. I can't see a seller listing that far below retail and still making a profit off of it, unless of course they're replicas which go for $60-$90 and ripping people off. Edit: Here are two different eBay listings showing an example of replicated serial numbers. Two different sellers, but the exact same serial numbers and questionably low priced.
Write down your Gucci product's serial number. The location of the serial number depends on the product. For example, serial numbers are engraved on the back of Gucci watches, while handbags feature a small leather tag stitched inside the cavity of the purse, with model and serial number information stamped in the material.
The serial numbers being near the buckle just indicate it's a newer model Imprime, older models have the serial numbers like yours in the middle of the belt. The devastating part is they both have 100% feedback, which goes to show how convincing 1:1 belts can be.