LC has provided a sample of how to punctuate a medley in the 505:
Song -- Song -- Medley. Song ; Song -- Song.
Also, please note that a CD with only 2 songs by one artist and no collective title doesn't need a 505 but should be coded:
245 10 ‡a First song ‡h [sound recording] ;‡b The second song / ‡c Artist.
740 02 ‡a Second song.
And a CD with only two songs but by different artists would be coded:
100 1 ‡a Artist, First. ‡4 prf
245 10 ‡a Song one ‡h [sound recording] / ‡c First Artist. ‡ b Song two / Second Artist.
700 12 ‡a Artist, Second. ‡t Song two.