The explosion damage: scales linearly with number of gloves, as seen from the formula
$$\text{BloodExplosionDamage}(n)=3.15 \times n \times (8 + \text{playerLevel}) \times \imagetooltip{Damage Multiplier}{https://res.cloudinary.com/dft1n3spr/image/upload/v1764501733/megabonk-guide/msyfbhopicnivvxuy6tk.png}$$
Bloodmark stacks: Each copy of slurp gloves applies 1 bloodmark stack to all hit enemies inside the explosion radius. So 2 gloves applies 2 stacks to all enemies in the radius. Effectively this just doubles the amount of damage done from the bloodmark stack debuff.
Healing: does not scale with number of gloves.
How much you heal always depends on your max HP and how many enemies are caught in the explosion. Does not scale with more copies
Cooldown: always 9 seconds, regardless of how many you have.
Radius: always 10, regardless of how many you have.