Sequence of tenses: I saw that the postman dropped some letters in our letter...

Do the sentences 1 and 2 pertain sequence of tenses?:

  1. I saw that the postman dropped some letters in our letter-box.
    ,the postman dropped’’ in the subordinate clause has a present meaning or past?

  2. I noticed that John entered the room. ,
    , john entered the room’’ in the subordinate clause has a present meaning or past?

I think that if both sentences pertain sequence of tenses, the subordinate clause has the present meaning, right? If not, please write for me these sentences in equivalent words.

  1. I am glad that I see you again.=
    a)I am glad to see you again. or
    b)I am glad to have seen you again.?

Thanks for help!

In #1, “the postman dropped” carries a past tense meaning. It’s a shorted version of “I saw that the postman had dropped some letters in our letter-box.”

The speaker is telling us that a some point in the past, he noticed that the postman had put the letter in the box at some point even further in the past.

In #2, everything is happening at the same time in the past. The speaker is reporting that he saw John enter the room.

For #3, either A or B will work. I’d be more inclined to use B if I was talking to the person again later, after we’d seen each other, earlier, but it could be used at the END of a face to face meeting.

Skrey, thank you for your help very much.
It’s confusing for me with these sentences, because for example in the sentence: I knew that John was in London, ,John was in London’’ has the present meaning in my grammar book and means, John is in London’’, and this sentence it is an example of sequence of tenses.
I thought that analogically will be with above sentences 1. and 2., why they are correct? bacause I would write them with Past Perfect:
,had dropped’’ and ,had put’’, and then it would be used sequence of tenses (meaning of Simple Past but changing to Past Perfect).