Freedom, Karen, thanks for the excellent tips and your help.

I did contact a local trainer from the website Freedom recommended, and started drilling both dogs (separately...) on basic commands to show who is boss

In the meantime, if anybody has had a similar situation of two same sex dogs suddenly turning aggressive with each other, please let me know, ...I would LOVE to hear some success stories about solving the 'violence problem'....there are plenty of internet sites with horror stories and advice to put one of the dogs up for adoption once serious fighting breaks out among same sex dogs (unthinkable for me personally...)...