In the sentence, “Agricola Servos Laborare Docuit,” Docuit is the main verb. Laborare is the objective infinitive. It says that a noun or pronoun in the accussative is the subject of the infinitive. This would be ‘Servos’. But if Servos is the subject then what is ‘Agricola’? Isnt Agricola the subject too? How can a sentence have two subjects?
Thanks.
servos is the subject of laborare; agricola of the main verb.
Edit: Oh no, Agricola is truly the main verb, but servos is a pure direct object and so it is laborare, for docere has a promiscuous constrution with two accustives: Doceo pueros litteras - I teach to the boys the letters;
so it translates as …teaches the slaves to work
However “Agricola servos male laborare dixit” would be just as you described, accusative with infinitive; servos being the subject of laborare, not of the main verb which is agricola.
I’m sorry for short spam of attention 
Let me ask a different question about this.
“The farmer taught the slaves to work,” has an infinitive as object.
How about this sentence, “The farmer forced the slaves to work.” This should be the same type of sentence. It has an infinitive as object yes?
Thanks.
I think it can vary on what verb you’re using, but acc + inf. is a safe bet.
doceo expresses both the people and things taught either in the accusative (the so-called “double accusative”) or with an accusative + infinitive construction.
agricola servos laborare docuit.
The farmer taught the slaves [how] to work.
agricola servos mathematica docuit.
The farmer taught the slaves math.
For the sentence “The farmer forced the slaves to work,” adigo (to compel) could probably take a multitude of constructions:
accusative + infinitive
agricola servos laborare adegit
gerund
agricola servos ad laborandum adegit
final clause
agricola servos adegit ut laborarent
I think “agricola” is the only subject. Laborare isnt subject, its a verb.
“Agricola”(subject - nominative) “docuit” slaves(servos - objective, accusative) laborare (another verb)