change MAC address for PPPoE connection

[Sergeant M.G.Bob]

Hello
I'm using PPPoE link to connect to the INTERNET. my problem is that I have
to change my MAC address for my night time link. I do that using ifconfig
command before connecting the night link:

*killall ppp
ifconfig cdce0 ether 2a:00:00:00:00:00
ppp -ddial adslnight*

cdce0 is the interface connected to the ADSL modem. command will change the
MAC address on the interface but PPP still uses the old MAC (I can see it
over tcpdump).
I think it's some cache or something that keeps the old MAC.
please help me, I couldn't find anything related on-line.

my ppp.conf:
*adsl:
  set log Phase tun command
  set redial 99 3
  set device PPPoE:cdce0
  set authname UserName
  set authkey Password
  set dial
  set login
  add default HISADDR

adslnight:
  set log Phase tun command
  set redial 99 3
  set device PPPoE:cdce0
  set authname NightUserName
  set authkey NightPassword
  set dial
  set login
  add default HISADDR*