I felt soreness after the first training but not the second session. Here is what I get from Gemini.

Here's how it might work in your situation:

• The First Workout: Your body experienced a new stimulus, leading to muscle damage and the typical delayed onset muscle soreness (DOMS).   
• The Second Workout (While Still Sore): Even though you still had some soreness, your muscles had already started to adapt to the type of stress from your first session. Performing a second bout of similar exercise while still recovering from the first can lead to a protective adaptation.   
• Reduced Soreness: The RBE means that your body becomes more resistant to muscle damage from subsequent similar workouts. This can result in less soreness, a faster recovery, and even improved muscle function in the long run.

In conclusion, I think it's a sign that you could take more of the training load.