If the IRS requires you to pay the estate tax and the donor's tax redundantly, aint that anomalous?

As I said in the other post when you asked a similar question, if you live where there are estate and donor taxes, the estate tax is applied first. If the heir (the spouse in this case, since there was no will) decides to transfer it to someone else (the niece in this case) the spouse could then be liable to pay a donor's tax. Even if you think they are happening at the same time, they will be handled as two separate transactions.