I ride multiple times in the day (self-employed) and almost always feel stronger on the second ride.

One of the things to watch doing multiple rides is refueling. You need to take in a lot of carbs, like several hundred calories worth every hour, depending on how many calories you are burning.

If you eat well between rides compared to before the first that might have something to do with it. In my case my metabolism is slow to get going. I'm not sure if that is a nutrition thing or just the way my body is. Whether or not that matters depends on what you are training for. I'm training for old age, so for me, it doesn't matter.

Training every day you don't want to do the same thing or you will overtrain. Just what you should do depends on what your goals are, i.e., what kind of riding you want to get good at. There are lots of specific training programs to look into for accomplishing different goals.

You you feel afterward will depend on what that day's training calls for.

Lots of references will get into nutrition and tell you that you need so many scoops of this and so many bars of that at certain times to maximize your training. That will work (at substantial expense) but you will never learn much about nutrition and how to eat doing that. Getting a good nutrition book, like Nancy Clark's, will teach you how you should eat. It gives you the same benefit as the engineered foods but more cheaply and is much healthier.

I feel like nutrition is at least a third of training. You have to know how to train, but you also have to know how to eat. Putting lawn mower gas in a race car isn't going to win any races.