See me once, an archive to some and container to others
See me twice, clumsily fight for my amphibious brothers
I'm trying to keep things hard enough for this community, but I'll be ready to post another verse tomorrow if needed.
If you are not familiar with my See me once riddles, I recommend you first have a look at the latest riddles in this series and their solutions:
#9, #10, #11, #12, #13