Inside of the Cathedral, like in so many old churches, we see a wild clash of styles.
That’s only natural in centers of power. Their rulers always had the money to spend, and often instead of building a new church in a new place, they chose to modernize one of the churches present.
Normally here in Europe the absence of a baroque altar in a romanesque church (or even the absence of gothic traces) indicates, that the church was given up (like it happened to some monasteries), or that the church is in a part of a country, that suddenly lost its dominant position. That’s what happened to south-western France, where you still see a lot of romanesque architecture, because in later times power had shifted to Paris and the money to modenize simply was not there.