  We present color-magnitude diagrams of globular clusters for models with
self-enrichment and pre-enrichment. The models with self-enrichment turn out to
have two or more main sequence turnoff points in the color-magnitude diagram if
the fraction of mass lost by the globular cluster under supernova explosions
does not exceed 95-97%. The models with pre-enrichment can have only one main
sequence turnoff point. We argue that the cluster wCen evolved according to a
self-enrichment scenario.
