D&D 5E Advice on ways to continue my adventure

[BlackSeed_Vash]

Thank you Imaculata for reminded me of Sliders. I really need to hunt that show down and re-watch it.

OT: Personally, going with a recharge timer (which is smart and simple) I'd not make it a hard timer. Instead, I'd allow the party to use the talisman before it was fully recharged, but I would stress that the farther from the fully recharged state the greater the chance of encountering negative events (like landing in the middle of a full scale battle), effects (Bestow Curse or 24 hours of the sickened state), or undoing some of their progress. In addition, the farther from the fully recharged state the more powerful the negative event, effect, or undoing is.

 

[Eltab]

Away from table, ask the player which of her character's two selves she wants to continue to play.

The other copy gets time-sickness and dies. Give this copy a chance to do something heroic on the way out - like a 'last stand'? - rather than being ignominiously consumed by flesh-eating bacteria.

Logically, it is easier to explain the "rescuer-self" dying, because the original continues without interruption. If the "rescued" self dies, soliloquize in the surviving character's name about how Tampering with the Flow of Time has unexpected - and drastic and BAD - side-effects. ("My younger self would still be alive if I hadn't interfered! She was supposed to escape to safety! I remember!")