Sorry for all of the posts today. Victor must have responded while I was writing.
I only know one person who was raised in this way. In her case, her father was Catholic and mother was Methodist. She may be an extraordinary case, but she was no less devoted to God than anyone I know who was raised in only one church. As she grew to an age where she was able to choose a church, she chose to attend the Catholic Church and is now married to a Lutheran. The difference is that she is understanding and loving of Protestant religions. This is not to say that all Catholics are anti-Protestant, but as stated by someone earlier (Benedict?), it tends to be more prevalent in cradle Catholics.