Answer
The graphs appear to coincide.
Work Step by Step
Please note that$$\sin (\alpha + \beta )= \sin \alpha \cos \beta + \cos \alpha \sin \beta .$$Since $1.2x+0.8x=2x$, we have$$\sin 2x= \sin 1.2x \cos 0.8x + \cos 1.2x \sin 0.8x.$$
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