Not Clear About This Query

select *From titles

(18 row(s) affected)

Totally 18 records are there in Titles table.

When I query

select title,title_id From titles where title like 'T%' and title_id
like 'M%'

It is returning 2 records.

So,now if I introduce a not in 2 places also it should return 16
records.
Whereas it is returning 14 records. What is the bestway to understand
this.

select title,title_id From titles where title not like 'T%' and
title_id not like 'M%'

Thanks
Ganesh