How do guns with multiple synergies work in Enter The Gungeon?

Some guns in Enter the Gungeon have multiple possible synergies triggered by other items or gun. In some case these synergies enable an alternate mode for the gun.

For example, Heroine - a gun based on Samus Arran's arm cannon - has three different synergies for also possessing three specific other guns. Reloading with a full magazine when holding one of those guns enable a secondary mode for Heroine (reference on the wiki: link)

• Ice Beam - If the player has Frost Bullets, enables Ice Beam mode, which fires a projectile that instantly freezes an enemy when fully charged.
• Plasma Beam - If the player has Hot Lead, enables Plasma Beam mode, which fires a fire laser when uncharged and a large piercing fire projectile when charged.
• Wave Beam - If the player has Shock Rounds, enables Wave Beam mode, which fires two wavy projectiles connected by electricity when uncharged, and a standard large Heroine shot when charged.

Megahand has a similar mechanic too, but offers even more alternate modes - eight. No surprise since the weapon is a reference to Megaman blaster.

The question is simple. Since the synergy is triggered by reloading the Heroine/Megahand gun while holding any of the three other guns... what happens if one posses more of one of those?

To put it more simply: what happens if the player qualifies for more than one of those synergy at the same time?