Contact macros in email template related to Calls module

Contact macros in email template related to Calls module

I have a following scenario when a (scheduled) call is being created:

1. the call is assigned to a Contact (call to)
2. the call is also assigned to a particular Deal
4. a custom Zoho CRM workflow sends an internal email notification
4. the email template contains Contact.First_Name and Contact.Last_Name information in the body of the email

the issue:
there are valid cases when the scheduled call is not assigned to a particular contact record. in this case the email template casts deal owner detail in Contact.First_Name and Contact.Last_Name. this is wrong.

is this tied to a particular logic I need to be aware or simply a bug? from my perspective the system tries to be too smart (by casting the deal owner details) as the values should stay empty - which was the expected scenario here.