To give you a “technical answer” both of them use the same Shoboi ID witch contain 25 episodes. Its probably because there isn’t a Shoboi ID for the TV version. If you go on Momokuri you will be able to see that the first version is matching with the Shoboi ID (number of eps). There is also another case where this can be added, some anime are separated by parts. One of the first anime that comes to my mind would be the season 2 of Re:zero where the first episode of the part 2 starts at 39 because it’s the continuation of the last episode of the first part which is the episode 38. Shoboi Part 2 episode list
Also, Momokuri wasn’t having the TV version in his relations so i am going to update it right now.