Because we are going as per the original Japanese TV broadcast.

Your "official" site is about the western broadcast of the series which is different.

Here are the informations about the original Japanese broadcast of this episode (it was initially a single one):

• the TV listing here: http://cal.syoboi.jp/tid/182/time
• the TV Tokyo website: http://www.tv-tokyo.co.jp/anime/pokemon_ag/3_back_num/0413.html

If the japanese broadcast is being used, then why do the seasons use the western organization? Also, the official Japanese website also lists these episodes (at 171 & 172), just in their "advanced" season, which includes the 4 Hoenn seasons of the western release. I used the western site as that seemed to be what TMDB was using in a way.

@Virch said:

If the japanese broadcast is being used, then why do the seasons use the western organization?

As indicated in the previous content reports, this anime is on our list of anime where the seasons should be reorganised. This will be done at a later date, not yet defined, by the administrator.

Also, the official Japanese website also lists these episodes (at 171 & 172), just in their "advanced" season, which includes the 4 Hoenn seasons of the western release.

As indicated above, we are going as per the original Japanese TV broadcast, not the way the show is currently listed. The original broadcast is described by the links in my answer above.

As visible on this snippet, this was originally a single double-length unnumbered special episode.