GO:0047290:   (alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3)-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity
Catalysis of the reaction: alpha-N-acetylneuraminyl-(2->3)-beta-D-galactosyl-(1->3)-N-acetyl-D-galactosaminyl-R + CMP-N-acetyl-beta-neuraminate = alpha-N-acetylneuraminyl-(2->3)-beta-D-galactosyl-(1->3)-[N-acetyl-alpha-neuraminyl-(2->6)]-N-acetyl-D-galactosaminyl-R + CMP.