hey mama,
this is sort of a hack but it works. i think what's happening is that when your first animation finishes and before it starts the second one, it reverts back to the avatar's current state, which in your case is a t-pose. so,set the avatar's state to whatever animation you're transitioning out of, in your case state(1) right before adding the action.
Code:
import viz
viz.go()
avatar = viz.add('vcc_male.cfg')
avatar.idlepose( -1 )
standing = vizact.animation( 1 )
walking = vizact.walkTo( [0,0,10] )
seq = vizact.sequence( [standing, walking] )
avatar.state(1)
avatar.addAction( seq )
best,
masaki