The second pictured Dendrobium speciosum plant looks like it could be Dendrobium xdelicatum, which is the natural hybrid between Den. kingianum and Den. tarberi (aka Den. speciosum var. hillii). The flowers are reminiscent of Den. kingianum, with slightly sparser flowering on the inflorescence.
Also, a few of the Ausie Dendrobiums are now classified under Thelychiton...