del=DeleteDuplicates@raw(*del=DeleteDuplicates@raw*)
del={{{"C",2}<->{"C",1},{"O",1}<->{"C",2},{"H",1}<->{"C",1},{"H",2}<->{"C",2},{"H",3}<->{"C",1},{"O",1}<->{"C",2},{"H",4}<->{"C",1}},{{"C",2}<->{"C",1},{"O",1}<->{"C",2},{"H",1}<->{"C",1},{"H",2}<->{"C",2},{"C",1}<->{"O",1},{"H",3}<->{"C",2},{"H",4}<->{"C",1}},{{"C",2}<->{"C",1},{"O",1}<->{"C",2},{"H",1}<->{"C",1},{"C",2}<->{"C",1},{"H",2}<->{"O",1},{"H",3}<->{"C",2},{"H",4}<->{"C",1}},{{"C",2}<->{"C",1},{"H",1}<->{"C",2},{"O",1}<->{"C",1},{"H",2}<->{"C",2},{"H",3}<->{"C",1},{"O",1}<->{"C",2},{"H",4}<->{"C",1}},{{"C",2}<->{"C",1},{"H",1}<->{"C",2},{"O",1}<->{"C",1},{"H",2}<->{"C",2},{"C",1}<->{"O",1},{"H",3}<->{"C",2},{"H",4}<->{"C",1}},{{"C",2}<->{"C",1},{"H",1}<->{"C",2},{"O",1}<->{"C",1},{"C",2}<->{"C",1},{"H",2}<->{"O",1},{"H",3}<->{"C",2},{"H",4}<->{"C",1}},{{"C",2}<->{"C",1},{"H",1}<->{"C",2},{"H",2}<->{"C",1},{"O",1}<->{"C",2},{"H",3}<->{"C",1},{"O",1}<->{"C",2},{"H",4}<->{"C",1}},{{"C",2}<->{"C",1},{"H",1}<->{"C",2},{"H",2}<->{"C",1},{"O",1}<->{"C",2},{"C",1}<->{"O",1},{"H",3}<->{"C",2},{"H",4}<->{"C",1}},{{"C",2}<->{"C",1},{"H",1}<->{"C",2},{"H",2}<->{"C",1},{"H",3}<->{"C",2},{"C",1}<->{"C",2},{"O",1}<->{"C",1},{"H",4}<->{"O",1}},{{"C",2}<->{"C",1},{"H",1}<->{"C",2},{"H",2}<->{"C",1},{"H",3}<->{"C",2},{"O",1}<->{"C",1},{"O",1}<->{"C",1},{"H",4}<->{"C",2}},{{"C",2}<->{"C",1},{"H",1}<->{"C",2},{"H",2}<->{"C",1},{"C",2}<->{"C",1},{"O",1}<->{"C",2},{"H",3}<->{"O",1},{"H",4}<->{"C",1}},{{"C",2}<->{"C",1},{"O",1}<->{"C",2},{"O",1}<->{"C",2},{"H",1}<->{"C",1},{"H",2}<->{"C",1},{"H",3}<->{"C",2},{"H",4}<->{"C",1}},{{"O",1}<->{"C",1},{"H",1}<->{"C",1},{"H",2}<->{"C",1},{"C",2}<->{"O",1},{"H",3}<->{"C",2},{"C",2}<->{"C",1},{"H",4}<->{"C",2}},{{"O",1}<->{"C",1},{"H",1}<->{"C",1},{"C",1}<->{"O",1},{"C",2}<->{"C",1},{"H",2}<->{"C",2},{"H",3}<->{"C",2},{"H",4}<->{"C",2}},{{"O",1}<->{"C",1},{"H",1}<->{"C",1},{"C",2}<->{"C",1},{"C",2}<->{"C",1},{"H",2}<->{"C",2},{"H",3}<->{"O",1},{"H",4}<->{"C",2}},{{"H",1}<->{"C",1},{"C",2}<->{"C",1},{"H",2}<->{"C",2},{"H",3}<->{"C",2},{"C",1}<->{"C",2},{"O",1}<->{"C",1},{"H",4}<->{"O",1}},{{"H",1}<->{"C",1},{"C",2}<->{"C",1},{"H",2}<->{"C",2},{"C",2}<->{"C",1},{"O",1}<->{"C",2},{"H",3}<->{"O",1},{"H",4}<->{"C",1}},{{"H",1}<->{"C",1},{"H",2}<->{"C",1},{"C",2}<->{"C",1},{"H",3}<->{"C",2},{"C",2}<->{"C",1},{"O",1}<->{"C",2},{"H",4}<->{"O",1}},{{"H",1}<->{"C",1},{"H",2}<->{"C",1},{"C",2}<->{"C",1},{"C",2}<->{"C",1},{"O",1}<->{"C",2},{"H",3}<->{"O",1},{"H",4}<->{"C",2}},{{"H",1}<->{"C",1},{"H",2}<->{"C",1},{"H",3}<->{"C",1},{"C",2}<->{"C",1},{"O",1}<->{"C",2},{"C",2}<->{"O",1},{"H",4}<->{"C",2}}}
show=Graph[#, GraphLayout->"SpringEmbedding",
VertexStyle->{{"C",_}->Lighter[Black],{"O",_}->Lighter[Red],{"H",_}->LightBlue,{"N",_}-> Lighter[Blue]},
EdgeStyle-> Darker@Green,VertexSize->{{"C",_}->0.7,{"O",_}->0.5,{"H",_}->0.4,{"N",_}->0.6},
ImageSize->{210,200}]&;
Multicolumn@DeleteDuplicates[show/@raw]@del]
Edit:
I don't know why you can't reproduce this.
I restarted my Kernels and got the same results.
$Version
show=Graph[#,GraphLayout->"SpringEmbedding",
VertexStyle->{{"C",_}->Lighter[Black],{"O",_}->Lighter[Red],{"H",_}->LightBlue,{"N",_}->Lighter[Blue]},
EdgeStyle->Darker@Green,VertexSize->{{"C",_}->0.7,{"O",_}->0.5,{"H",_}->0.4,{"N",_}->0.6},
ImageSize->{210,200}]&;
del={
{{"C",2}<->{"C",1},{"O",1}<->{"C",2},{"H",1}<->{"C",1},{"H",2}<->{"C",2},{"H",3}<->{"C",1},{"O",1}<->{"C",2},{"H",4}<->{"C",1}},
{{"C",2}<->{"C",1},{"H",1}<->{"C",2},{"O",1}<->{"C",1},{"H",2}<->{"C",2},{"C",1}<->{"O",1},{"H",3}<->{"C",2},{"H",4}<->{"C",1}},
{{"C",2}<->{"C",1},{"O",1}<->{"C",2},{"H",1}<->{"C",1},{"H",2}<->{"C",2},{"C",1}<->{"O",1},{"H",3}<->{"C",2},{"H",4}<->{"C",1}}
};
Quiet@DeleteDuplicatesBy[show/@del,CanonicalGraph]
DeleteDuplicatesBy[show/@del,IsomorphicGraphQ]
These are {1,2,5} of last del
.
If still have problems I may need to reinstall my Mathematica :).