Gen Longstreet authorized his own units that had "performed well" in either or both of those two engagements to place the honors upon their flags. That was the only criteria recorded that Im aware of. There were units that were not allowed to display the battle credit(s) that had less than favorable service on those fields.
These all appear to have been made and distributed to the units in question. The credits printed on strips of white cloth. Which then were sewn onto the obverse (front) of the flag only. Just an observation but appears if one had both credits, they were probably distributed on one single piece of cloth bearing both credits, one printed over the other. Apparently due to many variations thereof existing commonly gives the impression that that a directive advising how or where they should be attached probably wasnt included...
It appears the most common habit was to cut the two credits apart and apply one to the upper quadrant, the other to the lower. If just one credit can be found in either top or bottom quadrant.
I have seen at least two flags that this was applied as is with both credits still attached on one piece. In a couple of these flags that I have examined that the credits were separated, there were imperfections in the cut separating them. The other half showing the mirror imperfection of this single cut, giving further evidence that these were most likely handed out together on one piece.
Frederick