IXD2 available in 1939?

[CapZap1970]

Hello fellow Kaleuns:
some days ago, I asked about this, and our friend Jimbuna was trying to make me understand what to do without success in order to make this happen. The only thing is that I am stuck with the problem in the Basic.cfg file, where I find 2 entries for the same sub (look at the green text below) and I don't know which one to modify. Should I modify both? maybe delete 1 of them?
Besides, I am having a little truble trying to figure out what else must be added/modified in this file or other files. Any help about this will be most welcolme.
I hope Jim looks at this too.
Thanks a lot.
CapZap

[SUBMARINE2]
NrMinOff=3
NrMaxOff=5
NrMinPO=10
NrMaxPO=19
NrMinSeamen=24
NrMaxSeamen=32
NbVersion=4; 5
Version0=0 ; IXB
Name0=IXB
Month0=9
Year0=1939
Version1=1 ; IXC
Name1=IXC
Month1=7
Year1=1941
Version2=2 ; IXC/40
Name2=IXC/40
Month2=10
Year2=1942
Version3=3 ; IXD2
Name3=IXD2
Month3=1
Year3=1943
;Version3=3 ; IXD1
;Name3=IXD1
;Month3=10
;Year3=1941
;Version4=4 ; IXD2
;Name4=IXD2
;Month4=1
;Year4=1943