You're only aware of Republicans committing voter fraud for two reasons: Republicans prosecute it and the media reports it.  When Democrats commit voter fraud, they generally win the elections and are in charge if finding "evidence" of voter fraud and have nothing to gain by finding it and everything to lose.  So there is no evidence.

We need a federal database to be able to cross-check actual votes against eligibility, and cross-check to voters across all of the states.  Approximately 25 million people are registered in more than one state, and with mail-in ballots, it's easy to vote in more than one.  There is no system in place to cross-check.  There needs to be.

It isn't illegal to be registered in more than one state.  A lot of us move to another state and don't think to cancel our previous registration.  But it is illegal to vote in the state you left.  Enough Democrats with out of state ID voted in New Hampshire to swing the election.