Pandas Style DataFrame ValueError 'non-unique indices'

Pretty basic style value error, indicating that either the rows or the column titles are not unique, yielding:
ValueError: style is not supported for non-unique indices
#pandas #style #ValueError
Code I used below:
import pandas as pd
import numpy as np
np2=[]
for cd in range(0,21):
np1 = []
for as2 in range(0,10):
y = chr(x)
"Symbol7","Code8", "Symbol8","Code9", "Symbol9","Code10", "Symbol10"])

df2