[ahmedGYA]

The problem is, they check serial numbers with returns so bear that in mind when doing your se

I did a lot of things like, ordered the same product, sent back the old one to keep the new, and they never noticed

It works as long as the warehouse rep goes just for a general visual inspection.
Anyway, I've seen people peeling off the real S/N and sticking it on the returning item.

You could DNA the monitor, since you have a good account and its not too expensive.

never did a DNA, might sounds stupid but i don't know how does the method work

You just declare you didn't personally receive the package
However, amazon usually requires an OTP for products above 150€~ so check it in the checkout page if they'll ask it (a Yellow warning before paying).

I suggest you avoiding DNA if the OTP is required.

Spoiler:

An OTP is required for the BENQ ZOWIE XL2411P as of now.

You can sometimes avoid OTP by buying as a "gift". Thats how I DNAd my current monitor (250$).