There is a unsolved discussion by Tibetan authors on the identity of the Indian masters being addressed with the epithet nag po, see below:
In his Saṃvara history commentary, dpal 'khor lo sdom pa'i rtsa ba'i rgyud kyi don 'grel khog phub legs par bshad pa bde mchog rgyud bshad bstan pa rgyas pa'i nyin byed, a mes zhabs gsung 'bum [2000] (vol. 17, pp. 265-586), a mes zhabs ngag dbang kun dga' bsod nams/ (1597–1659) differentiates between (1) shar phyogs nag po pa (i.e. shar phyogs nag po pa/ ), (2) brtul zhugs nag po spyod pa (i.e. brtul zhugs nag po zhabs, nag po spyod pa/ (~late 8th/early-middle 9th cent. )) and (3) nag po dam tshig rdo rje (i.e. nag po dam tshig rdo rje/ (~10th cent.)) and his disciple (4) nag po shanta bhadra and a certain (5) nag po yun chen (grub chen ka la kA pa), see ...
On the identity of Nag po pa of the nag po lugs in the Hevajra transmission, see kye rdor dkyil 'khor gyi dris lan [2017] (pp. 385ff.), here (1) dam tshig rdo rje is identified as nag po pa che ba and a disciple of Virūpa, followed in the lineage by a certain (2) [nag po pa] chung ba dpal ldan zla ba; the author quotes here from old tantric material (rgyud yig rnying) and questions Ngor chen's explanation on this issue. He also mentions (3) nag po spyod pa, but not nag po zhi ba bzang po
According to the Fifth Dalai there were three Indian masters known as nag po pa: (1) nag po spyod pa ba is identified as the "greater/elder" (nag po pa che ba) and (2) nag po dam tshig rdo rje as the "lesser/younger" (chung ba). The name of the third one is given as (3) nag po lha las dad pa lnga pa chen po'i gsung 'bum [1991] (vol. 1, f. 176a)
bla ma dam pa bsod nams rgyal mtshan/ (1312–1375) identifies Kahṇa pa, that is shar phyogs kyi nag po pa in the text, as the "lesser/younger" (chung ba) ngo mtshar snang ba_A [Lobshe 1983] (p. 116)
see also "Kanha Name Confusions, HAR News, Sep 25, 2010":https://www.himalayanart.org/news/post.cfm?postID=248 (accessed: 2020-06-18)
Schott 2019 (p. 74 n. 183) states: "Tāranātha mentions Kṛṣṇacaryā as distinct from a later Kṛṣṇacaryā and that Kāṇha of the east, whom I supposed to be Kṛṣṇacaryā the Younger, has his own life-story in connection to Vīrupa, according to the Lamdre tradition."