Shiny Pokemon Silver Shiny Pokemon!?

Shiny Pokemon!? - shiny pokemon silver

After capturing the Golden Lake Gyrados anger, I went back to one catch and Noctowl Pokemon first time that I found was a shiny Girafarig, so I took it. I know that the probability of obtaining the Shiny Pokemon (except, of course, is Gyrados) in Pokemon Silver about 1 in 8000 something, then what are the chances of 2 shiny Pokemon in the same place in 3 minutes together?