[sdiy] Ring mod and op amp

[Seb Carr]

Hi all

i was just going over a ring mod schematic (Ring mod version 1 by Aaron
Cram, sorry forgot URL) and being a newbie with no elctronics training past
gcse i was confused by the out put of the LM13700: the modulator output
(from what i guess is a sort of buffering op amp) meets the outtput of the
LM13700 and on the schematic this is shown as two little circles
overlapping. Is this just a normal join in the wires/tracks or something
else?
    Also i came up with another thought: what would happen if you took 2
different signals and connected 1 to the inverting and one to the non
inverting inputs of an op amp?

Thanks for any help.

Seb Carr