Bug in DHCP OPTION 43 processing?

When using Vendor Class with OPTION 43, it seems that DHCP server is replying wrong.

In standard class the response looks like this:

Option: (t=43, l=5) Vendor-Specific Information (Alcatel-Lucent AVA)
 Option: (43) Vendor-Specific Information
 Length: 5
  Value: 3A020263FF
  Opcode: 58
  Voice VLAN ID: 611
  Type: Response from DHCP Server
 End Option
 Padding

Response in hex: 2B 05 3A 02 02 63 FF

When using Alcatel vendor class (that is, created a custom class with option 43) the response is

Option: (t=43, l=7) Vendor-Specific Information
  Option: (43) Vendor-Specific Information
  Length: 7
  Value: 2B053A020263FF
 End Option
 Padding

Response in hex: 2B 07 2B 05 3A 02 02 63 FF

As one can see, the response is, for some reason, double-processed, causing non-compliant response.

Is there something being done wrong here or what?