If you wire together two TTL outputs, which one wins?
The low one wins, TTL outouts have a stronger pull down than their pull up.

TTL inputs are current sources so they float high naturally.



when high there's 130 ohms and a diode between VCC and the output pin.
that's going to limit the high-state output current to about 25mA 

Combining outputs in this way will hurt performance, the device will produce more heat and probably be slower than if you used actual and gates to combine their outputs, bit if the main goal is to use fewer parts this can be a win.