Reselling and tariffs between China/UK and EU

If a reseller in England imports a widget from China they will pay the UK's China->UK tariff for that good.

If they then sell that widget to a customer in Spain (in the EU), will the Spanish customer then pay the China->EU tariff for that good, meaning tariffs are applied at two stages in the supply of the product, even though there is a free trade agreement in place between the UK and EU?

Does the situation change if the widget was designed and commissioned from the UK by the seller, but manufactured in China.