One way to explore this is to grab relevant segments of sequence from GenBank, e.g. the partial 28S subunit:
--> http://www.ncbi.nlm.nih.gov/nuccore/166361628?report=fasta
Copy that sequence and run a blast search:
--> http://genome.jgi.doe.gov/pages/blast.jsf?db=Glotr1_1
Within a few seconds you should get the result of this search. Even though the query is rather short (slightly over 1 kb), the result shows matches to three different contigs spanning the query (contigs 19158, 19242 and 19727) plus a bunch of much shorter and less significant matches.
Based on this very preliminary exploration, one could simplistically conclude there is evidence for just one copy of the rDNA sequence in this genome draft. On the other hand, if there are several nearly identical copies, they would probably be "over collapsed" in the unfinished draft, particularly if it is so fragmented in this locus.
At this point, it looks like the next step would be to try to figure out how much coverage there is for this locus relative to the unique regions of this genome. This would probably give the best hint to estimate the copy number.