Was Sarah a bigamist?

[GenesA]

This is quite a confusing situation, even to me, so apologies in advance.

Sarah Vaughton married Robert Storey on 8 January 1795 at Nuneaton in Warwickshire. Sarah was a spinster and Robert was a blacksmith of Tamworth. It doesn't seem like there were any children from this marriage. I'm assuming Robert died between 1795 and 1799 because Sarah married for a second time on 11 December 1799 at Tamworth to Thomas Silvester, my ancestor, and they had five children together. The marriage entry doesn't state the marital status of the bride or groom.

Sarah died on 1 February 1849 in Tamworth, followed by Thomas in 1851.

I haven't been able to find a burial for Sarah's first husband Robert but I found Robert in the Index to Death Duty Registers for 1825. He was of Tamworth and the administratix was Sarah Sylvester. Does this mean that Robert died in 1825, essentially meaning Sarah became a bigamist when she married Thomas Silvester in 1799?

[GenesA]

ADDED: The Index to Death Duty Registers gives Sarah's abode as Tamworth - not Robert. I have no proof that Robert died in Tamworth.

[Crumblie]

It could just be that by the time the death duty was sorted out she had remarried, it may be that the paperwork actually shows her as Thomas's relict (widow).

[GenesA]

That's definitely a possibility but supposing Robert Storey died sometime between 1795 and 1799, would it really take until 1825 for the death duty to be sorted out?

The problem is I can't find a burial for Robert Storey anywhere. The couple don't baptise any children in the area so it's like he disappears from the records immediately after his marriage in 1795.