This might be best answered by your VMware account rep (best place to make sure you are not in violation of something specific in all that licence text) - however from what I can tell it should work, if you setup your vCloud vCenter clusters to not include the extra sockets in question...
For example: (not saying this is a good setup, just one option I quickly thought of)
28 sockets using standard blades = 14 servers...
Cluster Mgmt - 4 blades
Cluster vCloud VDC A - 5 blades
Cluster vCloud VDC B - 5 blades
You would then only set vCloud to use the "vCloud" clusters - 20 sockets...