Complex sentence: Although, Peter claims meeting some Brigadier General Anis Nawab this may not have been his real name for Brigadier General is not a rank in the Pakistan Army and there was no Brigadier or General by the name of Anis Nawab in the Army at the time.
Split into simpler sentences: Although, Peter claims he met Anis Nawab this may not have been his real name. After all, Brigadier General is not even a rank in the Pakistan Army and there was no Brigadier or General by the name of Anis Nawab in the Army at the time.