Keep weighing her regularly as you are, at least once a week. I've not had little pigs myself, but those weights are small for 6 weeks, for both of them. Can I ask where you got them from? Her weight gain is good though. Someone with a bit more experience of young piggies will be able to advise further about the weights.
Like children (and any other animal!) some grow quicker than others, but you're right to consider that maybe the other is maybe dominating the food bowl.
You could introduce another food bowl, so that if this is the case, she still gets an opportunity to eat the pellets if the other piggy is being bossy over the bowl, or you could try scattering some pellets amongst the hay for her to forage for while she's munching.
Generally speaking, their diet should be at least 80% hay, 15% veggies and 5% pellets, so I wouldn't worry too much about her not eating many pellets if this hasn't changed (i.e. she was eating them but now has stopped). At this age pellets should be provided in an unlimited supply.
As long as she's getting an unlimited supply of good quality hay (meadow hay or timothy hay, with a handful or so of alfalfa hay added at this stage would be recommended), and she's eating her veg well and is getting some high vitamin C veg each day, I wouldn't worry too much about her not eating the pellets. She might be eating some, but just not many.
What pellets are you offering? Some are quite big for little pigs. There's a huge size difference between the original burgess nuggets and the blackcurrant and oregano ones. It might be worth trying some of the latter? I hear they generally go down well with young pigs and they're also quite small!
