You have: $(1, 3, 4, 5, 5, 6), (1, 2, 2, 3, 4, 5, 6)$
For $1,$ you can only have $6,$ and there is $1$ of them, so $1$ way to do this.
For $3,$ you can only have $4,$ and there is $1$ of them, so $1$ way to do this.
For $4,$ you can only have $3,$ and there is $1$ of them, so $1$ way to do this.
For both of the $5,$ you can only have $2,$ and there are $2$ of them, so $2 \times 2 = 4$ way to do this.
For $6,$ you can only have $1,$ and there is $1$ of them, so $1$ way to do this.
In total, there are $1 + 1 + 1 + 4 + 1 = \boxed{8}$
.