Confusion being created without any sound reason
Take a look at Bug # 267132 for Mozilla, Firefox and Thunderbird L10n CVS request for bn-IN and especially this. This could possibly top the list of the prime reasons FLOSS movements struggle to gain initial momentum.
One wonders how the poster of the Comment # 6 could be in a position to state with unequivocal conviction that The language od (sic) bn-BD and bn-in are absolutely same. .
The funny part in this entire imbroglio is that bn-BD was registered/requested much earlier to the Mozilla Localisation Project and nowhere was bn-IN mentioned to be an Ankur sub project. Unwarranted assimilation of any project related to Bengali (and Linux) had never been the hallmark of Ankur and this is one of those cases where it has been publicly displayed.