I believe that is normal for a vehicle that is present on the map without its crew, they could well actually be from the same platoon.....The C2 connection is to the crew rather than the vehicle itself.
The problem here is (I believe) that the campaign script for replacements here either affects the whole core force, or none of it.....The designer isn't able to specify which units are reinforced and which are not.
A way round this might be to remove all half-tracks in the core file itself, then add them as needed in the individual scenarios as non-core units attached to the core force. The downside of this however is that your half-tracks are now immortal and that they will be filled to the brim with ammo on each mission (the latter can be mitigated with the supply setting to some extent).