The cards drop two of their respective hearts every time.
Things that can drop pickups other than hearts will keep the same chance to drop a consumable, but with an increased chance for drops other than hearts and a decreased chance for heart drops. In particular, this increases the chances of acquiring:
Mom's Pearl or Bible Tract are trinkets which only need to be held to be useful, whereas Daemon's Tail is more effective if it is held and dropped at the right times, to get an increased chance for consumables from certain mechanics (to counter a lack of bombs/keys/coins, or to get Black Heart protection), and to still get enough heart drops to stay alive at other times (from bosses or familiars).
This trinket nearly requires this kind of strategy to pay off, making it tough to use as the player will have to sort and remember the moments where they must pick up or drop the trinket, as it interacts with nearly every consumable dropping mechanic.