In the movie Gattaca why did Vincent's father name him Vincent Anton rather then Anton?

He refers to Anton Sr. who is Vincents father.

When he finds out his first son (Vincent) have a 99% of heart disorder and has 30 years life expectancy, his father regrets that he did not take advantage of the technology (picking superior genes of the parents for the baby) to make is son "more perfect". Therefore, he does not think his disordered baby (Vincent) is worthy of his name, Anton.

When they (Anton Sr. and Vincent's Mother) have a second baby and they actually use the technology to make the second son (Anton Jr.) "more perfect", they then name him Anton because that is the "best" genes of the family in their son. They also think that Anton will be more successful so they give him "the superior name".