Answer
FALSE.
Work Step by Step
Take $f(x,y)=x$,
$$ \int_{0}^{1}\int_{0}^{x} xdydx= \int_{0}^{1} x^2dx= \frac{1}{3}$$
$$ \int_{0}^{1}\int_{0}^{y} xdxdy= \int_{0}^{1} \frac{y^2}{2}dy= \frac{1}{6}$$.
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