Ok. There have many songs which are "inspired" by others. Thats ok with me. If this is something more then band/record label who have rights to original song should get many for using their music. Ripping off is not good if original artist don't know about it (and say you can do this) or don't get money from them)work.
IF M.Martin gave BJ 90% of IML or D.Child gave BJ demo of Livin it's ok with me. BOn Jovi gave many song for others artists and thats also ok (Nothing, Cadilac Man, These Open Arms, One To Say Goodbye).Seb asked to show other band who have so many influences song as BJ... so for exampleLed Zeppelin
or Metallica (they ripped many more)
Billions of people think that Metallica made riff for "Ender Sandman but it's just ripped from Excel.
Some original versions of BIGGEST worlds hits. Listen before reading who ripped thats songs.
Many of biggest hits have "influences" from others artists fFor Example:
1 - Hotel California / 2 - My Sweet Lord / 3 - Ghostbuste / 4 - Surfin USA / 5 - Anybody Seen My Baby