Hexblade's Curse Damage

I had a thought occur to me today. I'm workshopping a Hexblade Hoplite build (because spear and shield is my favorite fighting trope). If I'm using Hexblade's Curse on a target as well as Hex or Spirit Shroud, do I apply my proficiency bonus once per weapon attack, or do I apply it to both the spear damage roll and the Hex/Spirit Shroud damage roll?

It feels like it shouldn't work twice, but it just says, "You gain a bonus to damage rolls against the cursed target. The bonus equals your proficiency bonus." I'm rolling damage for my spear and for Hex...is that one damage roll or two?

Thanks, all!