stylst2006.
I'm so sorry to hear both of your frogs have died.
It is VERY important to quarantine "the incoming" for at least 6 weeks- or more.
All we can surmise at this point, is that they both,probably, died from a "contagious" illness.

If you are tinkling of trying again, the quarantine period is a MUST.
If you are thinking about doing this shortly (?) the enclosure that they were in MUST be cleaned appropriately.

Lynn