There were a lot of songs submitted under different names and titles in the late 90s and 2000s. I'm not sure why, but maybe it had something to do with licensing? I just did a quick search, and it appears that Gary and Robert/Bobby are friends on Facebook. So maybe Bobby submitted it on Gary's behalf?
Maybe there was a licensing issue preventing them from using Gary's name so they used Bobby's name who submitted My Heaven to TWC under the title Pleasant Days on Gary's behalf after the latter recorded the song? Maybe it's just like how there were songs Incognito and Soul Café released on CDs submitted to TWC under different titles and under aliases CC Gilmore and Samuel Lincoln for Frank Josephs and Ray Herrmann, respectively. BTW, there did you find the Facebook page suggesting that Gary and Bobby were friends?
