Appointments+ sends duplicate cancelation emails

Hi,

I recently saw that appointments+ keeps sending duplicate emails on cancellation to our clients. The logs seem to look fine to me:

[5. November 2017 17:02] Die Bestätigungsnachricht wurde an r2210987@mvrht.net versandt, für die Termin ID: 5847
[5. November 2017 17:02] Removal message sent to r2210987@mvrht.net for appointment ID:5847
[5. November 2017 17:02] Client Max Mustermann cancelled appointment with ID: 5847
[5. November 2017 17:02] Notification message sent to info@birdconsulting.de for appointment ID:5847

I tried it with and without smtp plugin and on a dev page on the same multisite. same behaviour. And couldnt find anything on that topic on the community.

Can you recreate this behaviour?

best