The Oscar-winner, 65, joked that her husband, director Taylor Hackford, could not tell the difference and was "very taken" with the silent lookalike.
'My husband wants to marry her. I'm much more argumentative than she is,' The Daily Star quoted her as saying.
The waxwork took 20 modelers four months to make at a cost of 150,000 pounds and Dame Helen donated her favourite black Asprey lace dress for it.
The dummy will be placed in the museum's A-list room, which is designed to make visitors feel that they have stumbled upon a celebrity party.
Liz Edwards of Madame Tussauds said: 'Dame Helen has frequently topped visitor surveys to find out who the public want to see.'
Image: Helen MirrenĀ poses for photographers next to her wax model at Madame Tussauds in London on Tuesday. Photograph: Paul Hackett/Reuters
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