Is it good form/technique to punch and parry at the same time? Sometimes in Orthodox stance, I throw a left jab, and my opponent throws a jab simultaneously, I want to parry with my right hand. It becomes a double collision, and trying to prevent this. I have never seen this trained in practice, however seems reasonable.
It is quite common in orthodox approaches to parry and counter jab or catch and counter jab. It is a very useful technique in many circumstances.
The catch or parry can also be used to protect you very well from an opponent's counter whilst performing a basic jab, providing you don't overcommit and leave yourself open in other ways (described in more detail later).
Ideally, the parry or catch - at least in this approach - is a very minimal movement originating from the default defensive position of the right hand, which typically is attached to the right jaw, palm in.
From here, the hand is rotated clockwise 90 degrees and pushed slightly forward to catch, countering the incoming force, or pushed forward slightly with a simultaneous twisting and/slight downward motion to parry.
Be careful of parrying/catching more than a fist's distance from your chin. It should be a quick compact movement which enables rapid return to defensive position at the side of the head/jaw to protect against follow-up punches, especially hooks.
Some fighters will deliberately draw you into a parry or catch in the hopes of hooking around your right hand while you still have it forward of your head.
As you catch or parry, simultaneously throw your jab, for this is when your opponent is typically most vulnerable. An exception might be when you have fallen into a rhythm of sorts, and your opponent is beginning to anticipate your jab. In such a case it might be appropriate to delay your jab slightly, to ruin their timing and confuse their defence.
Keep your elbow in tight so that much of the impact is absorbed by your arm being braced against your torso.
May of the videos I've seen ignore these points, but I've attached some related material below:
Here's a jab-catch-jab combo.
A catch and counter with the right hand.