If you are losing conditon a lot playing two matches a day, use hard defensive/hard attacking, high pressing, hard tackling and man-to-man marking less. Maintain a large squad and rotate players. Use only light training between matches if they are close together. If you can, change one of the fixture times to give the squad more time to recover.
The game has made adjustments between all the playing modes and orders to make them more realistic, and with the latest training change, you now get 6% recovery every 3 hours instead of 5%.
This is a football management game, manage your team to cope with the workload they have to bear with the fixtures they play.
You're new here - welcome - have a look in the 'Tutorials and Guides' forum to get other advice on playing and team management.