There is no LEGAL prohibition on posting bail for more than one person. That doesn't mean you can AFFORD to do so. A bail bond company doesn't have to accept your business.

Sure, if the bail bondsman is willing to have them on the hook twice.

You're ALREADY on the hook for bail for somebody and you want to bail out him/her again ? WHY ? I highly doubt you'll find a bondsman willing to put up the bond again.