What you are asking for is not considered a Regeneration circuit. You can see Regeneration corcuit examples here:
http://www.hydraulicspneumatics.com/200/eBooks/ Look in the Fluid Power Basic link at Ch. 15 pg. 15-13 Fig's. 15-18 & 19.

I would call it a Transfer circuit and oil would only transfer from higher to lower pressure condition. Usually that requires an elevated pressure difference between the units (200-500 PSI) unless there is minutes to hours for the transfer to take place.
 

Bud Trinkel, Fluid Power Consultant
HYDRA-PNEU CONSULTING

Regen circuits by nature convert a double acting cylinder into a single acting cylinder when extending and use the rod area only as a force area, not the piston area.

I think you are looking for some type of flow divider circuit to keep the cylinders in parrallel when extending or retracting.  The key here is how much tolerance for inaccuracy do you have.  The more accuracy you need the more expensive this stuff gets. All the way up to feedback control circuits.

You can use a gear type flow divider which will divide and combine flows as the cylinders go out/in.  Accuracy 90% ?
Have to be carefull with pressure intensification and must put reliefs between divider and cylinders.  Also will have a problem with oil equalizing path of least resistance when cylinders are extended and loaded without some type of holding valve.  You now have to release the holding valve to lower the cylinders.  Gets complicated.

You could also try Some of Sun's Flow Divider combiners.  They have load holding capability and pretty good accuracy depending on the flow rate you push through them.  May eliminate need for load holding valves.