[Lazarus] How to get rid of duplicate ppu?

[Giuliano Colla]

Hi lazarus developers.

Since some time I get a number of annoying warning, whenever I 
re-compile Lazarus to include a package containing some customized 
components. Sort of:

The unit lazutf8sysutils exists twice in the unit path of the IDE:

1. "/usr/lib/lazarus/components/lazutils/lib/i386-linux/lazutf8sysutils.ppu"
2. "/home/colla/Applicazioni/Lazarus/Extra/lib/i386-/lazutf8sysutils.ppu"

Hint: Check if two packages contain a unit with the same name.

Of course I might select "Ignore All", but then I'd miss a real units 
conflict.

My components are derived from standard ones: I have a TButton1 derived 
from TButton, TLabel1 derived from TLabel, etc.
It happens that when compiling the package a number of standard units 
are compiled again, but ppu's go into my package's directory, so I get 
the same ppu's both in the standard lazarus tree, and in my package 
directory. This occurs both if the lazarus directory is writable, or not.

I tried to adjust search paths here and there, without success.
Could someone point me to a "clean" solution to this issue?

Giuliano