How to create \ssearrow with two heads

I'm using \ssearrow to denote a deformation retraction in algebraic topology. I want to use the same arrow, but with two heads for a strong deformation retraction. It doesn't exist in MnSymbol.

Is there a way to add another head to \ssearrow?

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\documentclass[12pt]{report}
\def\SSEarrow{\ensuremath{\rotatebox[origin=c]{-60}{$\twoheadrightarrow$}}}