Whenever you collect seed of anything, you want to know if the plant is a hybrid. Hybrid seed cannot be counted on to come true. If you want a crapshoot and just plant whatever comes up, then collect hybrid seed. If you want the same plant, you'll have to purchase the product.

Dan

'Rose Glow' is a common Japanese barberry cultivar. If you are in a state where this species is regarded as a nuisance maybe you shouldn't be raising more from seed.