I would be very cautious doing this. The Clown Pleco is only 3-4 inches but these are territorial fish, and will defend a patch of substrate near their favored retreat or hunk of driftwood from all other fish in the tank, moving along those as it can especially during feeding time. A corner 190 liter (roughly 50 gallons)may not have sufficient area (length and width is more important than volume) for this, especially if male. And if the second pleco is a male it too will be territorial.