May I ask what time period you are referring to? There was conflict within the church about when to celebrate Easter in the Early Middle Ages, but I cannot recall what you're describing. That said, Christian worship was hardly homogenized especially as it expanded eastward through Germany.

You may be confusing the Synod of Whytby. It was a council held by king Oswiu of Northumbria to determine the date of Easter. Due to Britain's distance from the heart of the church and the chaos left when the Romans left, British Catholicism began evolving somewhat independently from the main branch of Christianity on the continent. To compound this they used a rather complicated system to calculate the date of Easter as it wasn't a fixed holiday. Over time, Britain and the continent were celebrating Easter on different days, and even in Britain, depending on what tradition you followed (British or Roman) you may be celebrating Easter while your neighbor or even spouse is still practicing Lent.

And so Oswiu held the synod in order to hear scholars from both schools of thought and resolve this dangerous situation, as Easter is the most sacred of holy days to the medieval catholic and to practice it wrong whilst denying the right way was to endanger your soul. They all agreed that those who practiced it wrong out of genuine ignorance were to be forgiven as it was an honest mistake. In the end, Oswiu decided the church of Rome was correct on this matter and Britain was returned to the fold.