Belgian mechanised units equiped with the AIFV-B (from 86 onwards) have only the variant with the 25mm KBA autocannon. It would appear however that belgian mech platoons had 2 AIFV-B-25's and 2 AIFV-B-12.7mm's (instead of 4 AIFV-B-25's). The following comes from a detailed account of NATO forces in 1989. The zipped file is attached; you'll find this bit on page 122:
"Note 1: The AIFV-B equipped battalions had the following total equipment: 21 AIFV-B w/25mm gun, 21 AIFV-B w/12.7mm HMG, 6 M113A1-B w/81mm mortar, 3 M113A1-B-CP (command posts), 3 Scimitar, 2 Scorpion, 3 Spartan w/3 Recon Teams, 18 Milan ATGM, 36 Infantry Sections w/Blindicide, 4 trucks towing 4 4.2� mortars. TO&E: BN HQ: 3 M113A1-B-CP; 3 Cos, each HQ co (1 AIFV-B-25, 1 AIFV-B-12.7, 2 M113A1-B w/81mm mortar), 3 Platoons (each, 2 AIFV-B-25, 2 AIFV-B-12.7, 4 Rifle sections, 2 Milans); 1 recce co (3 Scimitar, 2 Scorpions, 3 Spartans w/3 Recon Teams), 1 Mortar platoon (4 truck-towed 4.2� mortars). M113A1-B-equipped units were similar, but substitute M113 for AIFV."
There is some corroboration as the belgian army seems to have bought both types:
http://www.answers.com/aifv
No figures on how many for each type of AIFV-B bought though.