The pronunciation of double consonants may be challenging for students who don't have double consonants in their own language.
From my experience as italian teacher I can state that everyone is able to pronunce them. It's just a matter of
1. get used to a new sound
2. practice : the more you practice this sound, the better you get with it. Also, the more you listen to this sound the more you'll get used to it (with time, a wrong pronunciation will sound strange to you)
Here are two tips to pronounce more easily and better the double consonants:
1. Consider that the vowel before the double consonants has a shortsound.
2. Exaggerate with the pronunciation of double consonants, don't worry about sounding funny or crazy. Exaggerate is not a mistake but the lack of pronunciation of one consonant is. Take your time to pronounce all the letters.