in some moments, we have two consecutive maneuver checks, like "knob hit". 1 check for the attack, one check for A2 resulting.
in my group when that happens we made the two checks. Is correct? Thankyou!

Yes, that is correct.
BTW, if the model is already knocked down and later pushed as a result of the blow effect just imagine the model rolls across the ground (and of course, ignore a repeated knocked down result ).

In the example you give the following happens:
The victim takes his MC (and the result of that MC is applied).
The victim suffers the attack as described in the Knob hit action.
The victim suffers the blow effect and may have to take another maneuver check.
If the victim fails the second MC (and was already knocked down) he "rolls" over the ground and is repositioned.
Keep in mind that if the victim fails his first MC and is knocked down he counts as being knocked down by the second MC (the one coming from the attack) and the Crowd Mood (and victim's and attacker's Pop) will be modified accordingly.

Understand?

i think i understand.
if knocked down for attack blow effect I modify again crowd mood and pop? or if thrown throuhg the air or dead?

thankyou tiger

You only modify CM as a result of a blow effect. Not because of a failed MC.
So if the victim fails his first MC (and is knocked down) and then, with the attack, suffers a blow effect he will always at least count as knocked down as a result and the CM will always be modified by at least 1 point.
Should he suffer such a great blow effect that he is thrown through the air the CM is modified by the normal +2 points. If the avatar dies because of the attack the CM is modified by +3.

understand now. thankyou!