Applescript conflicts between Firefox & Firefox Developer Edition

I have set a keyboard shortcut to show/hide Firefox. If i have Firefox Developer Edition active when I execute it Firefox Developer Edition gets hidden at the same time when Firefox appears visible. Applescript attached below:

tell application “System Events” to tell (process 1 where frontmost is true)
if name is “Firefox” then
set visible to false
return
end if
end tell
tell application “Firefox”
reopen – open a default window if there are no open windows
activate – make frontmost
end tell