Cluster Munitions - Capable to destroy tank?

[mr_clark]

According those lines I had an interesting event in my current 1989 SU vs UAE campaign. A 155mm Artillery round landed right on my A-ERA equipped T-64B1V and I got the message "Advanced ERA defeats Penetrator", that is, of course, what I expect the A-ERA to do for a normal AP/SABOT round. But is it intended that also an at least 20kg heavy Artillery warhead is defeated or does it has something to do with the game code "seeing" the penetration value on the 155mm round and thus handling it like a normal Antitank round?