Personally, I would let them know that you acquired the bag already and to just let someone else have it to sell or offer.
I ran into a similar scenario where an an advisor had told me if I wanted a bag in color X size Y and hardware Z; I kid you not, the very next day I was just browsing another Hermes location in the state and I asked about a bag and offered color X size Y and hardware A. I bought it and a few weeks later, I get a call from the first advisor on the other side of the state and let me know the bag came in for me and if I can pick it up. I felt so bad that they went through the effort to holding the bag or securing it for me on the upcoming inventory. I said I wouldn’t be able to since I just bought one the other day at a different location.
I don’t think they take offense, but perhaps it would be good to advise them so that you can continue to have a good rapport with them should you choose to down the road.
Note to this day, I still see both advisors and shop often, though my wallet may need a break as both locations are just opposites when it comes to stocks like I can go to both places and they won’t have what the other has and it’s funny to find what I want in one and what I need in the other.
I think with that my relationships with the two locations are good. We generally have things to talk about even if it’s not too personal and our rapport I feel is on the good spectrum enough so that I was offered another bag within a few days of getting offered a Birkin at another location.
Just be true to yourself though, if you feel a bit of guilt on hiding a bag you love and want to use then it’s probably best to come clean. Otherwise if you can totally just go in the store and never mention it, then that’s fine too. Think it’s all on personal preference (: good luck and definitely enjoy your bag!