The Bab claimed to be return of the Mahdi while Bab is also seen as forerunner to the Mahdi and door to him, hence Baha'allah as the Mahdi. In other words, two claims to the Mahdi.
The craziest thing about Bahai Faith is how they interpret day of judgment.
تَرَى الظَّالِمِينَ مُشْفِقِينَ مِمَّا كَسَبُوا وَهُوَ وَاقِعٌ بِهِمْ ۗ وَالَّذِينَ آمَنُوا وَعَمِلُوا الصَّالِحَاتِ فِي رَوْضَاتِ الْجَنَّاتِ ۖ لَهُمْ مَا يَشَاءُونَ عِنْدَ رَبِّهِمْ ۚ ذَٰلِكَ هُوَ الْفَضْلُ الْكَبِيرُ | You will see the wrongdoers/oppressors/unjust fearful because of what they have earned and it will befall them; and those who have faith and do righteous deeds will be in the gardens of paradise: they will have whatever they wish near their Lord. That is the mighty grace. | Ash-Shura : 22
Right now you don't see the oppressors/unjust fearful of what they earned. This is about the day of judgment.
وَتَرَاهُمْ يُعْرَضُونَ عَلَيْهَا خَاشِعِينَ مِنَ الذُّلِّ يَنْظُرُونَ مِنْ طَرْفٍ خَفِيٍّ ۗ وَقَالَ الَّذِينَ آمَنُوا إِنَّ الْخَاسِرِينَ الَّذِينَ خَسِرُوا أَنْفُسَهُمْ وَأَهْلِيهِمْ يَوْمَ الْقِيَامَةِ ۗ أَلَا إِنَّ الظَّالِمِينَ فِي عَذَابٍ مُقِيمٍ | You will see them being exposed to it, humbled by abasement, furtively looking askance. The faithful will say, ‘Indeed the losers are those who have ruined themselves and their families on the Day of Resurrection. Indeed, the wrongdoers will abide in lasting punishment. | Ash-Shura : 45
The disbelievers are not now in humble abasement.
اسْتَجِيبُوا لِرَبِّكُمْ مِنْ قَبْلِ أَنْ يَأْتِيَ يَوْمٌ لَا مَرَدَّ لَهُ مِنَ اللَّهِ ۚ مَا لَكُمْ مِنْ مَلْجَإٍ يَوْمَئِذٍ وَمَا لَكُمْ مِنْ نَكِيرٍ | Respond to your Lord before there comes a day for which there will be no revoking from Allah. On that day you will have no refuge, nor will you have [any chance for] denial | Ash-Shura : 47
This shows it's a too late scenario.
فَاعْتَرَفُوا بِذَنْبِهِمْ فَسُحْقًا لِأَصْحَابِ السَّعِيرِ | Thus they will admit their sin. So away with the inmates of the Blaze! | Al-Mulk : 11
So on and so forth.
Their concept of day of judgment contradicts the Quran in a clear manner, that you have to play games in your head with God's words, to convince yourself otherwise.
This is while we are living in the day of judgment time per Bahai Faith as it refers to the dispensation of Baha'allah to the next Manifestation.