I'm sorry that I didn't took part in this conversation for many weeks. The thing is that I have been extremely busy all this time. I hope that soon I will be able to write some comments to the messages here.
Right now I'd like to draw your attention to quite an intriguing fact. IMDb, the largest TV/movie database in the world, considers The Girl from Tomorrow and Tomorrow's End two seasons of one series. Its IMDb ID is tt0098803, see https://www.imdb.com/title/tt0098803/ and https://www.imdb.com/title/tt0098803/episodes/.
Interestingly, Tomorrow's End was previously considered a separate series by IMDb. Wikipedia provides its ID tt0101107 and a link https://www.imdb.com/title/tt0101107/. However, today this link is redirected to the page https://www.imdb.com/title/tt0098803/ which covers both seasons.
In my opinion, it'd be more correct to consider The Girl from Tomorrow and Tomorrow's End two separate series, as it was done before.
IMDb guidelines say:
source: https://help.imdb.com/article/contribut ... RK7YY47CQBHere are some of the criteria to consider when trying to define whether a series should be listed as one or two titles: the length of time that has passed between the seasons, significant changes to the credits including production details, how the series is marketed when released and perceived by the public and if there were any changes to the primary title.
I highlighted here the parts which, I think, confirm that The Girl from Tomorrow and Tomorrow's End are separate series.
I also draw your attention to the fact that some other series we are interested in are stored in the IMDb database separately:
However, Mirror, Mirror and Mirror, Mirror II are considered two seasons of one series: https://www.imdb.com/title/tt0112073/. Wikipedia gives an outdated link https://www.imdb.com/title/tt0127386/ to the 2nd part but it redirects to https://www.imdb.com/title/tt0112073/. I think it's better to consider Mirror, Mirror and Mirror, Mirror II separate series, just like The Girl from Tomorrow and Tomorrow's End.
***
I'd like to contact IMDb and suggest them to split The Girl from Tomorrow and Tomorrow's End (and Mirror, Mirror and Mirror, Mirror II as well) into two separate series.
What is your opinion on that?