In the movie Primer (2004), there are two main characters who travel back 24 hours in time using their time machine. When they arrive, both they and their past selves exist in this same town at the same time. Unbenownst to them however, one of the characters named Aaron has forgotten that he had his cell phone in his pocket when using the time machine. Both his cell phone and its molecular duplicate in the alternate Aaron's possession exist at the same time; likely both being in relatively similar vicinities (same town, less than ~20 miles apart).
After arriving back in the past, Aaron receives a phone call from his wife. Before time traveling, Aaron received this phone call previously while we was inside of a nearby hotel. However now he is receiving the call while outside, possibly implying that his double who is inside the hotel did not receive the phone call.
Both characters panic and discuss the ramifcations of what just happened. They are unsure of how cell towers work when it comes to having two identical receivers (phones).
In reality, what would/could happen in that situation? If you were to clone a cell phone, would both people holding the cell phone receive a ring? Would both people be able to pick up and speak? If one person picks up, does the ringing stop for the other? Does it depend on where both people are located (ex. closer person to the tower)? Is it possible to simulate this in real life (ex. duplicating the SIM card)? Why or why not and how, for any/all of those questions?