The simple answer is yes - all seedlings that come from parents that are hybrids themselves (ie all garden varieties) will also be hybrids, and are genetically unique. This is the case even if the mother plant self-pollinated its flowers. Even a seedling that looks identical to the mother to us is in these circumstances a new, distinct rose.

As I understand it, this is what separates the offspring from garden varieties from species roses, which if self-pollinated produce seeds that come true to the parent. So a wild R. Glauca for example, if it self-pollinates will produce offspring that "come true" as more R. Glauca, but if it was pollinated by a different wild species, or a garden variety, then the offspring are new hybrids themselves that are genetically different to the mother (and father) plant.

I hope that answers your question.