I don’t know if you’re still looking to solve this riddle but I believe the record for the 27th Foot is the correct one for you as I have located a discharge document for a John that reflects his almost 21yrs service in 27th Foot and the two marriages took place over 200miles apart! Unfortunately as the record is produced for pension purposes marriages aren’t recorded.
Although both records correctly place both events in the Principality of Bengal, matching both regiment’s [24th & 27th Foot] locations as given 10 Nov 1855, in earlier lists [2 June & 6 Jan 55] a more precise location is given that places the two regiments around 200miles apart:
24th Foot was at Peshawur, North-West Frontier Province, Presidency of Bengal, about 100mls from Kabul, Afghanistan. 27th Foot was at Sealcote [Sailkot], Punjab Province, Presidency of Bengal, 200miles SE of Peshawur.
Either both regiments coincidently had soldiers named John Teevan and fathers of the same name, or as both events took place in 1855, it’s a simple transcription error from when the IGI was collated; I’m sure checking the marriage registers in the British Library’s India Office collection would resolve the issue.
The record for 2656 Private John Teevan shows:
Born Parish of Anah [Anagh], Ballyhaise, Co Cavan, [Ireland] c1834. At the age of 18yr, he enlisted into 27th Regiment of Foot at Belturbet, Co Cavan 18 June 1852. He re-engaged at Fyzabad 4 April 1862 after 9yrs 244days service and went on to serve another “Discharged” at Curragh Camp 2nd August 1873 after completion of his 2nd period of period of limited engagement. Total service towards pension given as 20yrs 362 days [increased to 21yrs 14days at final discharge] of which 11yrs 171days was overseas service all in the East Indies [no dates]. Character was stated as good and in possession of 1 Good Conduct Badge and the India Mutiny Medal. His Conduct was stated as good – in possession of 1 Good Contact Badge. His name had appeared 18 times in the Regimental defaulters book and he had once been tried by Regimental Court Martial. At final discharge 19 August 1873, after administrations, he was described as: Age 39yrs 2mth, height 5 ft 10 in, dark complexion, eyes grey, hair dark brown, no marks or scars. His trade was Labourer. Intended place of residence Cavan Co Cavan.