One twin terrorising the other at night any help?

hey my girls are now 19 months sine 7 wks they have bot slept through and we have never had a problem with bedtimes however jasmine has started to literally terrorise faith at night she will steal covers and snuggles wake her upby pulling her out of bed stand faiths bed laughing while faiths stood next to the door screaming and nthing we seem to do helps we have tried putting her in a travel cot when shes have put her on aughty mat even resorting to putting her in a pushchair in the hallway on her ow just so faith can get some sleep we were going to try putting jasine to bed half hour early tonight then faith up later but by 6.30 faith is shattered and askin to go to bed but jasmine is no where near tired we have tried puttin each up when they say they are tired but when jasmine goes up she starts terrorising faith has anyone got any ideas??? also seperating them into seperate rooms is not an option as we only have 2 bedrooms