Code for adding a second legend without instantiating `legend.Legend`.

gistfile1.txt

import numpy as np
import matplotlib.pyplot as plt

lines = []
styles = ['-', '--', '-.', ':']
x = np.linspace(0, 10, 1000)

fig, ax = plt.subplots()
for i in range(4):
    lines += ax.plot(x, np.sin(x - i * np.pi / 2),
                     styles[i], color='black')
ax.axis('equal')

# specify the lines and labels of the first legend
leg1 = ax.legend(lines[:2], ['line A', 'line B'],
                 loc='upper right', frameon=False)

# Create the second legend and add the first manually.
leg2 = ax.legend(lines[2:], ['line C', 'line D'],
                 loc='lower right', frameon=False)
ax.add_artist(leg1)
plt.show()

Corrected version of code found in
https://jakevdp.github.io/PythonDataScienceHandbook/04.06-customizing-legends.html