There are two ways to give an entity a score (example:armor_stand):
scoreboard players set @e[type=armor_stand] score 1
scoreboard players set 0-0-0-0-0 (<–UUID of the armor_stand) score 1
Normally both scores are the same, just the way to find the entity is different
1. per Selector 2. per UUID
But it creates for the same entity another score
if you search the entity with the UUID 0-0-0-0-00 or 0-0-00-0-0 ...
it will always have different scores (default value = 0)