@Rui, 

Aha! I think your code explained the answer well. The interpretation difference should be the cause in my example.

Many thanks to you and @Marteen. 

@Rui and @Maarten, 

Thanks for your reply. I was originally testing what type of interpretation for the ":" will be in the second and third input, pattern or optional/default value. If it is used as a Pattern, the whole pattern expression seems to be one thing and can be replaced. If the ":" still indicates a  optional value, then the In[37] should be something like Optional[1,2] while one is tested and it passed test (Out[38]). I was wondering if the 2 can be the optional value of 1. Usually it should not happen since you will get an error message by doing this: 

I was confused by my results. (@Rui, your results are clear and the outputs are the same as they should be) 

Apololgize for missing the scenario here. 

I agree with Maarten about what the real question is. It would be easier to answer if one didn't have to guess what leads you to think it should return something different.
Do the results while replacing the Optionals by their first arguments confuse you? What about also removing the labels, and using MatchQ?
However, Optional's second argument not mattering for pattern matching is it's not as general as what Marteen said. Take