Yes you can but its not desirable. From experience it makes the plants more susceptible to mold, pest and disease, the more you clone from clones. What I mean by this is, take a clone from a seed. Let's call this a F1 or first generation clone ....then your mama dies or you flower it like you said you would like to do. That clone/F1 can be used as a mother but F2's will have slightly less to fall back on as far as its immune system for mold and pest resistance. Now, if you were to clone that clone and make F3sF4sF5s and so on its going to continue to get worse. Eventually the bud structure itself will start to change and quality will diminish as well. As far as clone only strains idk, never heard of them. You can purchase seeds of og kush and uk cheese online. I can post a site that has them all if anyone's interested. I cut clones and have a nursery. I only give out F1 clones so my genetics are strong and will smell, taste and look like the strain is described to look both indoor and outdoor by the breeders themselves.