You can't do 2 ammo types using only one unlockables entry. You also can't process 2 unlockable entries for one activity level. You can, however, do multiple unlocks for missions using sr2_city_missions.xtbl. I believe that a mission can process 4 unlock entries max.
The ORIG MISSION UNLOCK tab in my SR2 modding spreadsheet may help you out:
http://finalack.com/Idol/sr2/source/info_utils/SR2_MOD_DATA_v3.0.xls
Here are where all the diversion unlocks happen:
CHOP SHOP Complete any 1 Chop Shop list stat_unlockables.xtbl Diversion_ChopshopFirst (car_2dr_buggy01 variant race_fb) Buggy
CHOP SHOP Complete any 2 Chop Shop lists stat_unlockables.xtbl Diversion_Chopshop (sp_combine variant Reward) Kent (Combine)
CHOP SHOP Complete all Chops Shop lists stat_unlockables.xtbl Diversion_Chopshop_All 75% Mechanic Discount
HITMAN Complete any 1 Hitman list hitman_unlockables.xtbl Diversion_Hitman_1 Grenades at crib
HITMAN Complete any 3 Hitman lists hitman_unlockables.xtbl Diversion_Hitman_3 Satchel Charges at crib
HITMAN Complete all Hitman lists hitman_unlockables.xtbl Diversion_Hitman_ALL Infinite Rifle ammo
GANG KILLS 3 Gold Star Rank diversion_unlockables.xtbl Diversion_Combat Avenger Jacket
RACE Complete all motorcycle races racing.xtbl Diversion_Racing_Bike (bike_chopper01 variant gang_saints) Saints Race Bike
RACE Complete all plane races racing.xtbl Diversion_Racing_Airplane (plane_fighter01 variant gang_saints) Saints Plane
RACE Complete all helicopter races racing.xtbl Diversion_Racing_Heli (heli_4dr_police01 variant reward) Saints Helicopter
RACE Complete all boat races racing.xtbl Diversion_Racing_Boat (boat_yacht01 variant Gang_Saints_Racing) Saints Yacht
RACE Complete all car races racing.xtbl Diversion_Racing_Car (car_2dr_exoticsports05 variant Reward) Race car Bezier
RACE Complete all races racing.xtbl Diversion_Racing_All Special Cowboy Hat
BASE JUMPING 3 Gold Star Rank base_jumping.xtbl Diversion_Basejump No Fall Damage
ZOMBIE UPRISING Complete all levels zombie.xtbl Diversion_Zombie Zombie Mask
VEHICLE SURFING 3 Gold Star Rank diversion_unlockables.xtbl Diversion_Surf Traffic Cone Hat
HO-ING Complete Level 10 in Red Light District whoring.xtbl Diversion_Hoing Pimp Suit
MUGGING Complete 30 Muggings stat_unlockables.xtbl Diversion_Mugging Paintball Mask
MUGGING Complete 50 Muggings stat_unlockables.xtbl Diversion_Mugging2 Jane Valderama homie
HOLDUP Successfully hold up 20 Stores stat_unlockables.xtbl Diversion_Holdups Free Food and Liquor
AMBULANCE Complete all levels ambulance.xtbl Diversion_Ambulance1 (sp_ambulance01 variant reward) Saints Ambulance, Defibrilator
FIRE TRUCK Complete all levels firetruck.xtbl Diversion_Firetruck1, Diversion_Firetruck2 Saints Fire Truck, Fire Fighter Suit
HOSTAGE Complete 10 Hostage Diversions stat_unlockables.xtbl Diversion_Hostage (sp_atv01 variant hostage) Saints Toad ATV
TOW TRUCK Complete all levels tow_truck.xtbl Diversion_Tow (truck_2dr_tow01 variant gang_saints) Saints Tow Truck
TAXI Complete all levels taxi.xtbl Diversion_Taxi (car_4dr_taxi01 variant reward) Super Taxi
STUNT JUMPS Complete all 80 Stunt Jumps exploration_diversion.xtbl Diversion_Jumps_All (car_2dr_muscle02 variant Stunt Jump) The Duke's Bootlegger
COMBAT TRICKS Complete all combat tricks diversion_unlockables.xtbl Combat_TricksGun AR-50 XMAC Special
COLLECT CDs Collect 10 CDs items_3d.xtbl Diversion_CD1 Free music track Bachelor Samba
COLLECT CDs Collect 20 CDs items_3d.xtbl Diversion_CD2 Free music track Coconuts
COLLECT CDs Collect 30 CDs items_3d.xtbl Diversion_CD3 Free music track Marvelous Singers Remix
COLLECT CDs Collect 40 CDs items_3d.xtbl Diversion_CD4 Free music track Stereo Cha Cha
COLLECT CDs Collect 50 CDs items_3d.xtbl Diversion_CD5 All music free at Scratch That
DRIVING STUNTS 3 gold stars: oncoming, near miss, jump diversion_unlockables.xtbl Driving_Stunts (car_2dr_muscle04 variant Stunts) Bandit vehicle