Mrstigs My dcs have badges that have been 'superceded' ... so, when they get their '20 nights away' badge, then the '10 nights away' badge that is coming off the uniform goes onto the blanket, as an example.
Same with the 'participation' badges, as you only wear the current one.
They often will buy a badge at a campsite they have been to, as a momento/souvineer, and they go on.
Quite often there are occasions that are celebrated, where the badges are worn for that year - the Centenary (of Scouting) Badge was a good example, or last year's Diamond Jubilee badge, again, these go on when their 'time on the uniform' is finished.
Sometimes there are similar commemorative ones, if your dc's group has an anniversary or something more local.
Also they sometimes get a badge to celebrate a big camp, and they are only kept on uniform for that year, so then they go on the blanket.
Generally, blankets don't come into their own until they are Scouts, Explorers and Adults. There won't be many to come off during the time in Beavers, but may be some of the 'Staged' badges (they are turquoise with a purple border - for nights away, swimming, hikes, IT, First Aid, and music) as they go through Cubs.