Question

Some time ago the game show me all the units with double life bar. Does anyone know how to fix this?

Hello!
This issue appears to be unrelated and not caused by this mod (betterstats), although I will attempt to speculate on what's going on.

It could be that in your case there are two mods installed that have the same purpose (showing life bars), that are working simultaneously. My best guess would be to disable one of the two mods if there indeed are two separate mods that do this. Be it by uninstalling a mod or by disabling it in its settings (if such mod has such settings).
Personally I have not used such 'lifebar' mods in the past, do I do not have experience in which mods those could be.

Hello! This issue appears to be unrelated and not caused by this mod (betterstats), although I will attempt to speculate on what's going on.

It could be that in your case there are two mods installed that have the same purpose (showing life bars), that are working simultaneously. My best guess would be to disable one of the two mods if there indeed are two separate mods that do this. Be it by uninstalling a mod or by disabling it in its settings (if such mod has such settings). Personally I have not used such 'lifebar' mods in the past, do I do not have experience in which mods those could be.

Probably, the problem is that since I am playing the Prominence Hasturias Era modpack I don't know if it is possible to disable a mod since everything comes together and it is a problem I have recently, since at the beginning only one life bar was displayed correctly.