The same design number on different parts?

[Magnus Forsberg]

Following the decision of how to name the stud on the minifig heads 3626a/b/c,
I've found that the same design number is used on more than one part.

We have at the PT six heads with numbers (part alias):
10756, 46506, 86294, 89510, 90787 and 99570

A search on those numbers at Brickset shows cgi-pictures of both 3626b an 3626c heads;
10756 (design number), leads to 6006387, (item number) and shows a 3026c-head.
46506, (4200908) shows a b-head.
86294, (4549621) shows a b-head.
89510, (4578503) shows a b-head.
90787, (4584727) shows a b-head.
99570, (4651443) shows a c-head.

A search at Bricklink of the item-numbers leads to both 3626b and 3626c heads;
6006387, leads to 3626cpb719 (and a reference to 3626bpb719 as a similar design)
4200908, leads to 3626bpb122 AND 3626cpb122
4549621, 3626bpb366 AND 3626cpb366
4578503, 3626bpb332 AND 3626cpb332
4584727, 3626bpb471 AND 3626cpb471
4651443, 3626bpb633 AND 3626cpb633

Are TLG using the same design and item numbers on more than one part?
How do we handle that in our library?

[Philippe Hurbain]

Using a, b, c... suffix?

[Chris Dee]

I am more inclined to believe the Brickset data, since it comes directly from LEGO. The Bricklink relationships _might_ be assumptions.

[Philippe Hurbain]

Mmhhh.... See these parts:
http://www.bricklink.com/catalogItem.asp?P=14769pb004
http://www.bricklink.com/catalogItem.asp?P=4150pb148
Images were supplied by the same guy so we can be pretty sure that both type exist. But Brickset list only one design and item:
http://brickset.com/parts/design-16424
These design numbers are those of patterns, not shape if they are equivalent.

[Michael Heidemann]

http://brickset.com/parts/design-16424
These design numbers are those of patterns, not shape if they are equivalent.

I guess that this design numbers covers both design and shape. Only the pattern does not make sense to me.

[Philippe Hurbain]

More precisely: they mean the pattern on funtionnally equivallent parts. For heads, stud type really doesn't matter. It's more questionnable for round tile 2x2...

[Stephan Meisinger]

Lego does not (always) track mold variants. Currently they still deliver b-type heads. Even thourgh at least for me this was very rare in 2013. As far as a I know there doesn't seem the be a system for this (or at least it isn't public - coule be possible they also have an interal number). My observation(!) was light flash variants tend to be c-types, while yellow counterparts have a higher b-type percentage. At least for me, but this may be luck. I could also confirm b/c-types are mixed in one set - even for the same print and design id. (Seen on 9471: Uruk-Hai Army)

Bricklink does track mold variants but for the heads they are not a very accurate source (they tend to use b-type even on newer sets). They don't seem to have an alternative system for the minfig (or they don't use it)