
If you add another coin on the "Undetermined" year line the the 2 green check marks become 1 green check mark meaning "I own a coin of this type" even though you still own a coin of each strike.

If you start with only 2 of the 3 coin year lines there will be 1 check mark. If another coin is added using the "Undetermined" line it changes to two check marks even though you don't own a coin of each strike.