我有以下df：
url='https://raw.githubusercontent.com/108michael/ms_thesis/master/crsp.dime.mpl.abbridged'
zz=pd.read_csv(url)
zz.head(30)
date feccandid feccandcfscore.dyn pacid paccfscore cid catcode type_x di amtsum state log_diff_unemployment party type_y bills years_exp disposition billsum
0 2006 S8NV00073 0.496 C00000422 0.330 N00006619 H1100 24K D 5000 NV -0.024693 Republican rep s22-109 12 support 3
1 2006 S8NV00073 0.496 C00000422 0.330 N00006619 H1100 24K D 5000 NV -0.024693 Republican rep s22-109 12 support 3
2 2006 S8NV00073 0.496 C00000422 0.330 N00006619 H1100 24K D 5000 NV -0.024693 Republican rep s22-109 12 support 3
3 2006 S8NV00073 0.496 C00000422 0.330 N00006619 H1100 24K D 5000 NV -0.024693 Republican rep s22-109 12 support 3
4 2006 S8NV00073 0.496 C00000422 0.330 N00006619 H1100 24K D 5000 NV -0.024693 Republican rep s22-109 12 support 3
5 2006 S8NV00073 0.496 C00000422 0.330 N00006619 H1100 24K D 5000 NV -0.024693 Republican rep s22-109 12 support 3
6 2006 S8NV00073 0.496 C00375360 0.176 N00006619 H1100 24K D 4500 NV -0.024693 Republican rep s22-109 12 support 3
7 2006 S8NV00073 0.496 C00375360 0.176 N00006619 H1100 24K D 4500 NV -0.024693 Republican rep s22-109 12 support 3
8 2006 S8NV00073 0.496 C00375360 0.176 N00006619 H1100 24K D 4500 NV -0.024693 Republican rep s22-109 12 support 3
9 2006 S8NV00073 0.496 C00375360 0.176 N00006619 H1100 24K D 4500 NV -0.024693 Republican rep s22-109 12 support 3
10 2006 S8NV00073 0.496 C00375360 0.176 N00006619 H1100 24K D 4500 NV -0.024693 Republican rep s22-109 12 support 3
11 2006 S8NV00073 0.496 C00375360 0.176 N00006619 H1100 24K D 4500 NV -0.024693 Republican rep s22-109 12 support 3
12 2006 S8NV00073 0.496 C00113803 0.269 N00006619 H1130 24K D 2500 NV -0.024693 Republican rep s22-109 12 support 2
13 2006 S8NV00073 0.496 C00113803 0.269 N00006619 H1130 24K D 2500 NV -0.024693 Republican rep s22-109 12 support 2
14 2006 S8NV00073 0.496 C00249342 0.421 N00006619 H1130 24K D 5000 NV -0.024693 Republican rep s22-109 12 support 2
15 2006 S8NV00073 0.496 C00249342 0.421 N00006619 H1130 24K D 5000 NV -0.024693 Republican rep s22-109 12 support 2
某些行是彼此完全重复的。有没有办法删除重复的行？