If you are not sure, and it is within a few hours of possible ingestion, you may want to see local vet for possible induction of vomiting of both dogs with apomorphine, just to be on safe side if one or both ingested these items (1800petmeds.com)
These signs can develop quite rapidly, but if the item ingested has a low level of Xylitol, symptoms may be delayed as much as 12 hours from ingestion. (kellysdogtraining.com)
The amount of xylitol found in different products — even different flavors of gum — can vary widely, so having information about the item ingested, how much was ingested and knowing your pet's weight is important. (aspca.org)