Invoice is being printed locally even when output type is not triggered

Good Evening!

We are facing a strange situation where some of our Invoices are getting printed locally even when the output type is not triggered.
Users are triggering an output type A which is used to send email to their customers.

But when they do this an invoice is printed locally in their printer which is of output type B.

There is no trace of B anywhere(header output of invoice, the spool for the user)

Both output type A and B use the same smart form.

Please let me know if anyone have observed this behavior and kindly provide your valuable inputs.

Thanks,

Theerthesh Kumar Jain