The white one had a patch on blood on its fur the other day, had a look and its got a scab type thing there now. God knows how it got there, but id noticed a few smudges the week before. it seems to be healing now. Are they fighting?
Ive had them maybe 6 weeks and they came to me at 8 weeks old.
They could be fighting, have you noticed them getting in each others faces with each other, literally nose to nose and then raising them up as far as they can go, or does one seem to to be totally domineering?
Are there any sharp edges in the hutches the other one could have got caught on? Are their nails being kept short? Are their teeth still short? These are all possibilities or if you have not seen them fighting the most likely cause could be mange, these are mites that live in some hay and can bite (very similar to fleas) causing scabs and scratching, it is easily fixed by the vets.
If they are fighting to the extent of drawing blood you can try and give them seperate areas to go to e.g. two bottles, two bowls etc but it may be they have to be seperated if it gets no better. Unfortunately some pigs just don't get on even if they are related.