Find&replace does not find 'double' but finds 'do'

[altair]

(do|double|xxx|yyy|ccc|ddd€€€€€€€€€€€€|iiii) in find & replace finds all the words I told them to search except “double.”

Do is found.

Is it because of the same beginnng?
But I have it written whole!

Please, can someone help me do the trick?
MANY THNKS!

[arnaud.versini]

I think (do(uble)?|xxx|yyy|ccc|ddd€€€€€€€€€€€€|iiii) could be better for this research

[altair]

I wrote (ccc|(do[b-u]*)|xxx…) and it accepted, in that case.

[altair]

Just tried what You said! Sure goes!
MANY THANKS!!!