[Machine] During the time of Umar ibn Al-Khattab, people used to offer twenty-three units of prayer in Ramadan. It was possible to combine the two narrations (regarding the number of units) because they used to start with eleven units, then perform twenty units before ending with three units of witr prayer. Only Allah knows best.
كَانَ النَّاسُ يَقُومُونَ فِي زَمَانِ عُمَرَ بْنِ الْخَطَّابِ ؓ فِي رَمَضَانَ بِثَلَاثٍ وَعِشْرِينَ رَكْعَةً وَيُمْكِنُ الْجَمْعُ بَيْنَ الرِّوَايَتَيْنِ فَإِنَّهُمْ كَانُوا يَقُومُونَ بِإِحْدَى عَشْرَةَ ثُمَّ كَانُوا يَقُومُونَ بِعِشْرِينَ وَيُوتِرُونَ بِثَلَاثٍ وَاللهُ أَعْلَمُ