If, on the other hand, both numerical parts of your key are variant then you can split on the hyphen and do numerical sorts on each.

knoppix@Microknoppix:~$ perl -E '
> my %seq = map { $_ => 1 } qw{
>    1035-2341
>    1047-835
>    1035-2347
>    874-3971
>    1035-65
>    874-70
>    1035-46
>    };
> say for
>    map  { $_->[ 0 ] }
>    sort { $a->[ 1 ] <=> $b->[ 1 ] || $a->[ 2 ] <=> $b->[ 2 ] }
>    map  { [ $_, ( split m{-} ) ] }
>    keys %seq;'
874-70
874-3971
1035-46
1035-65
1035-2341
1035-2347
1047-835
knoppix@Microknoppix:~$
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I hope this is helpful.