so i somehow ended up with 2 of these from this event i looted one and the postmaster sent me one xD can i use them both or with the weekly reset can i use it after the event ends?

It is weekly quest only allowed to turn in once. Can only turn these in during the specific timewalking event.

but after the event end on tuesday arent they there for 24 hrs more so couldnt i say turn in a second?

If I remember correctly. Once the week long event is over, they either do 1 of 2 things.

1) Vanish from your bags
2) Stay in your bags unable to start another quest until it is the same weekly event(since each even has a different weekly turn in quest item)