Ok so im confused by all this "master code lost" stuff the search function gave me.
So the current GoG and Steam versions are patch 1.5 and its actually an unpatched game with a few improvements? Then i read the steam version is 1.6, whats been done there? And how. if the source code was lost. I am confused. In other words is there a version of the game, combining all, both patch 1.34 and patch 1.5 and maybe some more fixes?

PS i have a 1024x768 monitor and the 3cd version.... in some cellar box.. i hope

The current GoG and Steam releases of DD are at the same game version (1.0062A). The latest 1.0062A patch finally fixed the ingame music. The source of 1.004A (it is the most interesting game version but sadly no one keep this distribution) and 1.005A was lost so 1.006A is a new re-build with fixes from 1.005A. The main patch that fixed the majority of bugs in CD game release was 1.33 (or 1.0033A in game menu, not 1.34). 1.0062A doesn't include the fixes from CD release patches. In other words, the 1.0062A is an equivalent of 1.0029A with HD resolution support and few other fixes but without fixes from 1.0033A. Beware! 1.0062A dropped Win'98/ME and Glide support! Then You're lucky. Install it, patch to 1.0033A (1.0034A) and play. You don't need GoG or Steam releases.

Thanks, i had hoped there would be a completed digital solution to that, now i have to go clean the cellar -,-

The 1.33 patch had a compatibility bug with previous save versions, which for some people could cause the fog of war to be reset and quest opened location to be resealed (new games started in 1.33 were fine). The 1.34 patch fixed that. It does, in fact, contain some of the fixes and changes from the 1.32/1.33 patches.

. Unfortunately not, but if you do not need widescreen or higher resolution support, you can stick to the disk version. The CD version may already be updated, depending on when it was produced.

It's incorrect.
1. 1.0031A and 1.0032A (1.31&1.32) are not a patches but officially called 'hotfixes' which fixed small amount of critical bugs from 1.0029A. The first patch for the game is 1.0033A.
2. 1.0034A is a second patch for the game and (apart from fixing insignificance) has removed Safedisc v2 copy protection. I know this. But it is not a bug but a feture of this version (1.0033A). You should start a new game with this version. That's all. I don't see the point in playing from older saves with unfixed bugs. :-) If You start a new game there are no differences between 1.0033A and 1.0034A. And playing from older savegame is highly not recommended anyway.

Officially, Larian was not allowed to release any patches for the game for a while after release, because the publisher thought that would imply that they released buggy games. So Larian released 'hotfixes'.

Oh... my... word! Publishers!