If both are DTs, yours and the Siegel illustration. The real question is, to which DT, Siegel, yours or another one (or all) was used by Scott to list the DT.
A price of "-" just means there is not enough information or demand for an item to determine a useful value, be the item rare or quite common. See the first paragraph of "Understanding valuing notations" on the
Scott Numbering Practices and Special Notices pages beginning on page 19A in the 2022 US Specialized. Remember the same number of each type of double transfer and short transfer were produced so one is initially no more or less rare than the others but retention after 140+ years can change those numbers. Now demand, that is hard to determine with something that is not traded much due to the specific DT. My belief is many want 185 and are happy to get one and if it has a DT or short transfer, the comment is, "oh" if they notice. Few are looking for this DT/ST only on 185s.
One needs to look in the early documentation to see how these plate varieties were discussed as they were unearthed, noticed and written up. That will be a challenge in of itself.
Me, I am looking for a DT on a pre-185 item which is dash listed in Scott also. The only copy I have seen sold (Siegel power search was a bust, 67 pages and two lots not illustrated with only a 50-50 chance the described stamps two were what I want) was on
ebay and for condition (so-so), it went just over catalog of a normal item. What makes my search hard is it is for a position which many collectors did not save because even if pristine, it was not a desirable item to fill one's page's space.
Edited for more power search detail.