Merge failed for custom checkbox

[Snook]

SugarCRM Version 4.5.1f

Hello,

On accounts form, I have 2 custom checkbox. When I merge 2 duplicates accounts, which have both these 2 checkbox checked, the new account have these 2 checkbox unchecked !
If I change the value "Duplicate merge" for these custom checkbox, the merge work correctly but then I cannot control the merge for these field.

Any ideas