Four ground guns in Medium Airfields are stacked on top of each other, at least in the Crater terrain.
F18GNG000
F18GNG00A
F18GNG00B
F18GNG00C
Then the gun number jump to F18GNG010, F18GNG011.
I checked three Medium Airfields using Destroy Object and had this problem.
If you use another gun to destroy the F18GNG000, the host doesn't report the other 3 guns destroyed, however, if you use restore, you can bring the other three back up.