I think you'll need to clarify what you mean when you say 'tap'. That term has 2 primary uses when discussing beer service systems, neither of which seems to apply in the context you present.
The term 'tap' typically refers to either:
a) the faucet assembly, sometimes including the shank
b) a sankey keg valve/fitting
However, based on the context of your post it sounds like you are talking about trying to find a way to use a single regulator to send pressure to 2 different kegs. That is typically handled by using a manifold or a wye splitter.
One item of note: in order to pressurize 2 corney kegs at different PSI you need at least 2 regulators. 'Turning down' the pressure on a line requires regulation-- only partially opening a valve doesn't change the pressure of the delivery.