You have two types of Butter Picks - your one tine and your two tines (both 5-6 inches). My research tells me that both are used with a piece called a butter pat. This utensil is used to lift the butter from the pat.
One Tine in Repousse by Stieff
Two Tine shown in Frontenac by International (5 1/4 inches)
Butter Pat shown in Stieff Rose by Kirk Stieff (3 1/8 inches in diameter)