He went out, investigated, and found: any act of Bais Din; this should be returned - נפק דק ואשכח כל מעשה בית דין הרי זה יחזיר
There are two possible cases here. Either the woman is claiming the גט with a הנפק and the proof that is necessary from כל מעשה בי"ד is that we are not חושש שמא מאחר נפל. Or if the שליח is requesting the גט without a הנפק, then just as by מעשה בי"ד there is no concern for נמלך, similarly once the שליח has the גט there can be no concerns. There is a difference whether someone is claiming that he lost something, which we found (where he is believed), or whether we are told that a person died (where there is a concern, maybe it is someone else).
We never signed, only on one Get, etc. - מעולם לא חתמנו אלא על גט אחד כולי
The husband claims these עדים signed on my גט. The husband is never suspected of lying; however when the עדים do not testify, we are concerned that perhaps the husband assumes its his גט, however when they testify that they only signed on one גט, he will never say they signed on mine unless he is sure.