Need Help With Strange Multi-Phase Plug
Depending on the year built this could have been a totally coda compliant multi wire branch circuit. The red being 1 leg and the black being a second leg with the white neutral common to both circuits. In the past the breakers did not require handle ties for the last few code cycles this has been a requirement. Some electricians will split the hot tab on an outlet and wire the top outlet in kitchens with 1 leg and the bottom on the second . others would wire every other outlet with 1. Then the other on the next. All of this was up to code and before the late 70's gfci's were not required. Installing GFCI'S on multi wire branch circuit can be problematic.