distortion with lm386 in parallel
Per the datasheet, you cannot adjust the gain with only a resistor.  There must be a capacitor as the only, or one of the gain set components because that circuit also is involved in setting the output pin DC voltage 1/2 way between the power pins.  Connecting only a resistor upsets the gain at DC and the output bias point.

A Zobel network should go from each output to that chip's ground pin, not between the outputs.

Add decoupling capacitors to each chip, as close as possible to the power and ground pins.