The two blocks A and B of equal mass are initially in contact when released from rest on the inclined plane. The coefficient of friction between the inclined plane and A and B are ${\mathrm{\mu }}_1$ and ${\mathrm{\mu }}_2$ respectively.

If  ${\mathrm{\mu }}_1>{\mathrm{\mu }}_2$  the blocks will always remain in contact

If ${\mathrm{\mu }}_1<{\mathrm{\mu }}_2$ the blocks will slide down with different acceleration if present.

If ${\mathrm{\mu }}_1>{\mathrm{\mu }}_2$ the will have a common acceleration $\frac{1}{2}\left({\mathrm{\mu }}_1+{\mathrm{\mu }}_2\right)\mathrm{gsin}\mathrm{\theta }$

If ${\mathrm{\mu }}_1<{\mathrm{\mu }}_2$ the will have a common acceleration $\frac{{\mathrm{\mu }}_1{\mathrm{\mu }}_2\mathrm{g}}{{\mathrm{\mu }}_1+{\mathrm{\mu }}_2}\sin \mathrm{\theta }$