Which leads to disastrous results, if you have passive buzzer connected thru transistor

For example,

PIC16F1828.

Sound PORTB.6,[115,1] - ok
Sound PORTB.6,[116,1] - port is left high

So when called, first statement works fine, if 2nd statement uses same frequency, it is also fine, but if 2nd statement uses different frequency, then port is left high. However, if I call the statement 3rd time, again, with different frequency, then port is turned low.

Technically, this is not a big issue - I just modified my code and added LOW PORTB.6 everywhere, after the SOUND statement, but I'm curious, is this bug or a feature?