Thank you for contacting us.
Currently there is no straightforward/easy way to set automation ID for the DayCells.
However in your particular scenario (automating day cells for a calendar) this can be achieved by some custom logic in your tests handling such scenario (two objects with the same automation ID). The idea is when requesting a particular day first to check the count of objects returned with some particular ID (1 from the attached image). If there is only one - you can safely use it, in case that there are 2 such objects, you can just get the first or the second, depending exact day that you want to get.
I hope that this suggestion is applicable to your scenario.
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items