In Andrew and Gordievsky's history of the KGB in 1990, Bim Bom is identified as an individual (not a pair), who had been shot at by Cheka operatives during a performance in Moscow in 1918.
ɪn ˈændɹuː ænd ɡoːɹdˈiːvskiz hˈɪstɚɹi ʌvðə kˌeɪdʒˌiːbˈiː ɪn nˈaɪntiːnhˈʌndɹɪd nˈaɪnti, bˈɪm bˈɑːm ɪz aɪdˈɛntᵻfˌaɪd æz ɐn ˌɪndᵻvˈɪdʒuːəl nˌɑːɾə pˈɛɹ, hˌuː hɐdbɪn ʃˈɑːt æt baɪ tʃˈɛkə ˈɑːpɚɹətˌɪvz dˈʊɹɹɪŋ ɐ pɚfˈoːɹməns ɪn mˈɑːskoʊ ɪn nˈaɪntiːnhˈʌndɹɪd ˈeɪtiːn.