In the East 12th Ave example it is just one-site of the duplex, for what you desire you may wish to expand your search into â€œincome propertiesâ€ where duplexes, triplexes and multi-family may be listed. If I may offer a few additional thoughts:
Leases: If considering a duplex be sure to review the existing leases as leases in Colorado remain intact at time of purchase. Look for terms such as â€œdelivered vacantâ€ or similar. Yet due diligence is important as I have seen leases with options and renewals which can impact the immediate and future value of the property.
Legal Duplex: During due diligence I always suggest a review of public records to make sure the additional unit is truly legal and conforms to existing zoning or is grandfathered in. There are Denver neighborhoods which encouraged duplexes i.e. the former R-2 zone district however other zone districts i.e. the former R-0 and R-1 allowed only a single-family even if there was an auxiliary unit. Thus future subdivision or even present rental could be an issue.
I may suggest employing the services of a broker who understands the complexities concerning income property, duplex, subdivisions and zoning, your search may be lot easier and more production. In addition as a broker I have on behalf of clients contacted owners of such properties advising of potential interest of a buyer even though not on the market. This is common in Cherry Creek and other areas with a concentration of duplexes from the post WWII period when R-2 zoning was in force.