I'll try not to be too long.
Until 1993 Andorra, a handful of valleys on the Pyrenees, was a feudal state. Coming from a 1276 agreement (called "Pareatges" in Catalan) between two Catalan feudal lords: the bishop of la Seu d'Urgell and the viscount of Castellbò; whose legacy ended into the French Crown and from it to the French Republic President. Both were equal and indivisible lords of Andorra, and were called "Coprínceps", as Andorra is a principality. As none of them lived in Andorra, they appointed two representatives in Andorra: the "Veguers" (a political figure common in all Catalan lands, as Andorra is). They were called "Veguer francès" (for the French head of state) and "Veguer Episcopal" (for the bishop). They shared the power and acted as co-heads of state.
After the 1993 constitution the power of coprínceps, and so that of the veguers, become just representative, as in any other full right democracy.
In Andorra the domestic mail is free, the foreign is provided by the French and Spanish POs. But Somehow, in the late 1970's there appears a "Vegueria Episcopal Issue Service" that began to issue cards like this one (issued in 1986)stating that the card covers the domestic mail fee (it's free!) and that for foreign mail, a suitable stamp should be affixed.

Later there appeared also some minisheets like yours. A lot of people here (in Catalonia) collect them as they show Catalan subjects (normally neglected bu the Spanish PO that we bear). Not me, although I like and pick them whenever I find at a good price. For me, they are halfway between cinderella and postal items.
Your first sheet deals with the Roman Law from which Catalan Common Law (and, hence, Andorra's) comes; and the second one, on "Andorra" as a subject of French and Spanish operas.