organic chemistry of alkyl halides and alcohols
You are correct that copper metal is a catalyst for alcohol dissociation to aldehyde + $\ce{H2}$.  The reaction of ethanol, for example, can be written as:


$$ \ce{CH3CH2OH  -&gt;[\ce{Cu}~\textrm{metal}][300~^{\circ} \textrm{C}] CH3CHO + H2} $$


Your question about halo-substituted alcohols is very interesting, because those species are very unstable.  If I understand you correctly, you are not referring to halohydrins such as 2-chloroethanol, which are species that have a halo substituent beta to the alcoholic carbon, but rather to species such as 1-chloroethanol where the halo and hydroxyl substituents are on the same carbon atom.
alpha halo alcohols are very unstable, and tend to eliminate halo-acid and form the corresponding carbonyl compound.  For example, gaseous chloromethanol spontaneously eliminates hydrogen chloride to form formaldehyde at 296 K (~23 &deg;C) with a half-life of about 300 seconds.
Thus I think the best answer to your question is that:


Halo alcohols like 1-chloroethanol or chloromethanol are already oxidized to the same degree as carbonyl compounds.
Even before reacting them with copper metal at 300 &deg;C, they are likely to decompose to the carbonyl compound via elimination of hydrogen halide.
Unlike the reaction of simple alcohols on hot copper metal, this reaction is not a redox dissociation, but is a simple elimination reaction.$%edit$