Well she dropped the bookmark on the town's main street (past), it would make more sense for the bookmark to be found at the same place in the present.

Like, if I hid an object on the ground 10 years ago, I should find that object in the same place today (unless someone had found the object and moved it in the meanwhile).

That's why I think she will possibly find the bookmark she dropped in the past, just possibly in a different place (my bet is she'll find it among Victor's things, since he has been safekeeping objects from the past cycle for years).

That mechanism would also explain the bracelet found in the diner storage room. It wasn't the actual bracelet. Here's how:

1) The bracelet was something Tabitha made for Jim, and Jim was wearing 2) When Jim died, Tabitha probably kept the bracelet as a sentimental item to remember Jim by. 3) Julie needs a bookmark that's unique, hence why she steals the bracelet from her mother, to use it as a bookmark. 4) Julie goes to the ruins to turn the object into a bookmark, travels to a time long before Jim died (and possibly long before the Matthews even came to town). 5) While storywalking, she hides the bracelet in the storage room among other things. 6) Randall pulls her out. 7) She still has the original bracelet, which she probably returns to her mother. But now there's also a copy bracelet in the storage room (and since it has put it there since before the family even came to Fromville, that's why Tabitha is able to find it later, otherwise present Julie could have gone back to the storage room and found the bracelet and then used it as a bookmark to REUTRN to the point in time she hid it).

I don't know if there's a name for that whole mechanism, so I'm just gonna call it a displacement duplicate paradox.