List 5. Arrange 8 cards $A A B B C D E F$ in a row, the number of arrangements where the same letter cards are allowed to be adjacent is how many?

Arrange 8 cards $A A B B C D E F$ in a row, with the same letter cards allowed to be adjacent. How many such arrangements are there?
Let the number of ways to arrange 8 cards in a row be $S$, then $|S|=\frac{P_{8}^{8}}{P_{2}^{2} \times \bar{P}_{2}^{2}}$; let the situation where the two cards with the letter $\Lambda$ are adjacent be $A_{1}$, and the situation where the two cards with the letter $B$ are adjacent be $A_{2}$, then $\left|A_{1}\right|:=\left|A_{2}\right|=\frac{P_{i}^{\rangle}}{P_{i}^{?}}$.

If both the two $A$s and the two $B$s are adjacent, the situation is $A_{1} \cap A_{2}$, and $\left|A_{1} \cap A_{2}\right|=D_{6}^{6}$, and the situation where no identical letters are adjacent is $\overline{A_{1}} \cap \overline{A_{2}}$. By the principle of inclusion-exclusion,
$$
\begin{array}{l}
=5760 \text { (ways). } \\
\end{array}
$$

That is, there are 5760 arrangements that meet the requirements of the problem.