I, on the other hand from sooeithdk, regard the first as misleading, almost completely wrong. And why? Because Carl does not stand in any sort of equivalence to the clause that follows the comma. The sentence is not a parallel to the following type of constructions, where the single comma makes sense:
After the death, Carl was trying to hire more workers.
During the strike, Carl was trying to hire more workers.
Standing on a beer barrel, Carl was tryimg to hire more workers.
Carrying a pink parasol, Carl was trying to hire more workers.
I therefore prefer your second construct because it clearly equates "Carl" to "the owner". The use of both commas rather than one parallels the parenthetical sentence "Carl (the owner) was trying to hire more workers." This makes the meaning entirely clear.