It is possible to set it up so that specific tills use different prices for same PLU file. This way you can keep the PLU files in sync between the tills while still offering price difference between them. The way this works is by setting up a modifier that is permanently on and will change the price of the desired PLUs automatically. Because of how modifiers work we can easily set it so it works only on specific PLUs and Tills.
To start go to PLUs etc./Modifier and add a modifier. Set the Scope to 9 - Global so it works continuously, make sure the rest of the settings are set so the price is adjusted correctly. A price shift is probably the easiest way.
Next go to PLUs etc./Departments and enable the modifier for the areas needed.
Finally go to Operators etc./Operator Groups and enable the modifier again for the Operator groups used. Set it to 2 - Automatically so the modifier is always enabled. This is where the ECRs will differentiate, ensure the tills that need the price adjustment have this enabled while the till that don't, have it disabled.
Additionally, go to Print/Output formats and under PLUs etc., expand the Modifiers and set the modifier you made to 0 so it doesn't print anything additional.