The DM decides which languages an orb knows.
The description of the Professor Orb states (Waterdeep: Dungeon of the Mad Mage, p. 284):
The orb speaks, reads, and understands four languages [...]
It gives no guidance concerning which languages or which types of languages are eligible, so the DM determines which languages an orb knows. Additionally, as a Professor Orb does not require attunement, there is nothing preventing a character from owning two Professor Orbs, except of course, the DM. If the DM wants to give out two orbs, then they can.