两个都正确，但意思是不一样的，具体的不同如下

more popular中文意思是更受欢迎，更流行的

Some minority languages are losing their identities because of the invasion of more popular spoken ones.

more and more popular中文意思是越来越受欢迎

While "future mail" is becoming more and more popular, some people are wondering what will happen if the postal address changes or if the company goes broken before the letters arrive.