Dat tuuschen bi us is eenfach. Wenn du wat duppelt hest to'n tuuschen, denn laat di den Opkleber in usen Kataloog wiesen un änner dat van "Kiene Duppelten" op "Tuusch ik". Dat geiht denn van sülben in diene List un jedereen kann dat sehn.
And when you like to have a label, that is shown in a tradelist of an other collector, than you can change "✘" to "✔". Labels you like to have are then in your WHISHLIST and your tradeparter will see this label(s) in his REQUESTLIST. That's it.
To reduce the number of labels of huge tradelists, you can change "I don't have it" to "I have it". Labels you do have will not be displayed in any tradelists. That way you do not need to check labels you already have again.
Labels you do not like to trade because they are too similar to existing ones or of a kind you do not collect (i.g. Wrappers, Boxlabels, Misprint, etc), you can hide in the tradelist. So, if you see such labels in the tradelist you do not need, then click "Show it" and change it to "Omit it". In the filter criteria of a tradelist is the default to display only labels that are not omitted. I you like, you can change this filter to see labels you have omitted in the past.