There is no possibility of naval vessels with the same name. But in case of Tokusetsu Kansen, there is possibility of requisitioning ships with the same name. If there are ships with the same name in the Navy, confusion is inevitable. So the Navy renamed the ship internally without changing her registered name.
The first case of renaming was Tokusetsu Suijoki Bokan, “Noshiro Maru”. She was called “Noshirogawa Maru” till 20 August 1941 because the same named ship had been in service as Tokusetsu Sokaitei. She was newly enlisted into Tokusetsu Junyokan on 20 September 1941, but not renamed in that time. Tokusetsu Sokaitei, “Noshiro Maru” was renamed “Dai 2 Go Noshiro Maru” vice versa.
Except the case of “Noshirogawa Maru”, the Navy distinguished a ship from the same named ships by adding “Dai 1 Go”, “Dai 2 Go” or “Dai 3 Go” to her original name.
Japanese --> English
Dai 2 AAA Maru --> AAA Maru No 2
Dai 2 Go AAA Maru --> AAA Maru 2 Go
Dai 2 Go AAA Maru --> AAA Maru No. 2 Go
When you find “AAA Maru No. 2 Go” in this site, the ship is renamed. “AAA Maru 2 Go” and “AAA Maru No. 2” are her original name.
There were some Tokusetsu Kansen which were added “I Go” to their original names. The navy originally added “I Go”, “Ro Go” or etc. to a ship requisitioned by the Ministry of Navy except Tokusetsu Kansen.
The owner changed the registered name from “Kyokuto Maru” to “Ohyashima Maru” (Tokusetsu Unsokan) on 15 January 1942, but the Navy continued to call her “Kyokuto Maru” giving the different Kanji character from the original one. As well the Navy continued to describe “Manjyu Maru” as “Santos Maru” (Tokusetsu Sensui Bokan).
See Table 2 for renaming of Tokusetsu Kansen.