Tomatoes - same variety, different looking plants!

Hello all
I'm an inexperience tomato grower and need some reassurance. For the first time, I have grown my tomato plants using seeds from last years fruit. I grew red and orange varieties and was very careful to keep the two separate. However, the plants are now 4-6 inches tall and doing really well, but the orange variety has different coloured stems. Some are a plum coloured and others are a bright leaf green. It's possible I got a couple of seeds mixed up, but it's about a 60-40 split across 30-odd plants. Is it normal for infant plants to show this variation?

 

Stems and leaf veins can sometime look purplish if the plant has had a chill.
There are other reasons no doubt.

 

Seed saved tomatoes can throw up all sorts of variation, especially if there was any cross pollination last year. Tomatoes are mostly self pollinating but bees do cross them occasionally. The purple stems on their own aren't a worry though, Pete8 is right that a bit of cold can cause that. I'd grow them all on and see what you get, might end up with something interesting.

 

Thanks guys! I will certainly grow them on as it will be interesting to see how they turn out. Cross pollination sounds highly likely as the red and orange plants were grown side by side last season. I wouldn't be worrying, but I've got so many plants that I'm giving lots away and don't want to give someone orange when they wanted red!

 

I bought some Bloody Butcher tom seeds a few years ago. The first year's fruit was nothing like it should have been but the following year produced the correct fruit. Some kind of mix up with the supplier but a bit odd.
I've never tried saving and growing seed from shop bought toms as I can rarely find anything which has a flavour.
I'd do as others suggest and just continue with what you have - if they are doing well, it would be rather a waste to worry about the colour - if they taste like "proper" tomatoes then job done
As said, some purpling of leaves/stems is common enough if you have experienced some low temps.

 

Many supermarket tomatoes are created for them by breeders and are F1 Hybrids.
Seed from any F1 tomatoes will not come true to type but will have characteristics of the parents - which can be good or bad.
Seed saved from Heirloom varieties will come true.