...Came back with two.
Meet "girldog", an elderly, pretty overweight Staffie cross that was loose and limping slightly in the park. Dog Warden was closed (I missed the end of their office hours by forty minutes or so). Outside she seemed fine with Lola, but growled at both dogs individually when I had her on-lead in the house, so she's currently relegated to the 'dog room.' Poor old girl just wants to lie on my lap for scritches, but I can't stay upstairs with her because I can hear Ro shrieking bloody murder downstairs.
I couldn't leave her there at the park though (she's like my Jess - an old lady Staffiemix, and if Jess--or Lola--ever got loose I'd hope someone wouldn't leave them out overnight), so she's here until the morning, when I ring the dog warden. At least, with her apparent unease/wariness toward my dogs, I won't be tempted to add a third to the mix.
I have exactly zero self control when it comes to loose dogs.