You can't delegate same sXFI and LPT to different validators, only to one, means, if you have for example 1000 sXFI and 10 LPT, you can delegate 900 sXFI and 6 LPT to validator A, and the rest, 31 sXFI and 4 LPT, to delegator B, but you can't delegate already staked sXFI or LPT to another validator.