They don't appear to be F1 hybrid seeds, so its certainly worth saving some and trying them next year.

They should come more or less true from seed, unless someone was growing regular sunflowers within a quarter mile, which may result in a variety of heights due to cross pollination.

thanks for the advise, once again you have come through for me, i will give it a go harvesting some, but have a couple of packets on stand by. once again thank you ,
steve

if the dwarfing trait is genetically recessive then yes they will come true. providing it has only been pollinated by 'dwarf' pollen.
but if it isn't fully recessive you may well get a range of heights and colours. it will be fun to find out so collect some seed and give it a go.

I planted a pack of 'Teddy Bear' Sunflowers once. 1/4 came out 3 ft tall and fully double, as the packet says, 1/4 were 6 ft. tall and single, and 1/2 were 4 ft. tall and semi-double. Never found out if that was sloppy breeding on the seed grower's part, or what. The seed company said that they had never heard of such a thing...riiight! :/