In QC I don't know but in campaign mode, this can occur and there's a reason, I suppose it's the same problem.
In the artillery facility, it's coded in which direction objects are oriented. This means that all guns that will be called will be turned in the same direction for that facility.
But, if guns models are not coded the same (front is 0° for the first one and 180° for the other one) then, one will be correctly oriented in the facility and the other one will be opposite direction.
The only solution is to edit facility and replace the generic #static_artillery pickup by a specific artillery gun. Doing this, you are sure that guns will be always correctly oriented but you will have less diversity. This is a choice to do.
Hope I've been clear in my explanations!:mixedsmi: