Is it possible for a lab to damage a partial denture impression by pouring the wrong material?

Lab impression: Yes, it's possible. It doesn't happen too often but it can happen.

Unlikely: Stranger things have happened but I have never seen this.

Anything is possible: The older i get the more i realize that almost anything is possible. Never say never. Any time a model is poured, there can be damage to the impression. Some impression materials are more fragile than others. Therefore, some allow for re-pouring of the model while with others, once the model is poured, the impression is ruined and cannot be reused. Hope this helps.

Yes: The impression is best poured up only one time.

Yes: This is possible. It can also be the technique that is used.

Of course: Not only pouring, even the temperatures exceeding 60°C/140°F will damage partial denture impression.