We have traveled Colombia and know something about the DIAN - customs and
about the country.

As per a previous SELF IMPOSED agreement, I will not express my opinion here, but ask several questions instead. I am not sure what your question is? If your question is in regard to "insurance" just because a policy has been written for each bike does not mean it covers a new owner. This is sort of a no brainer, so I suppose your question has to do with the legality of purchasing a bike, bikes, in Colombia.

This question would be impossible to answer without knowing the country of registration of the 2 bikes and a little of the history of ownership/nationalities of the previous owners and the bikes.

Are the bikes Colombian registered? Or, were they entered into Colombia on a TVIP.
(Temporary Vehicle Import Permit)? And, what are the buyers nationalities and official status in Colombia? This question could have several answers... Colombian, tourist , permanent foreign resident, etc. Each of these answers might effect dramatically the purchase of 2 bikes in Colombia.

As you are aware, by previous post it is mandatory to compare actual vin and license plate data with any documents that come with the bikes. And, know if the bikes were entered into Colombia on TVIPs you must check the dates on the TVIPs to make certain the bikes have not overstayed in Colombia. Also, if Colombian registered bikes you must check to see if persons with your official status in Colombia is permitted to exit a Colombian registered bike/bikes from Colombia.

The DIAN was very helpful to us when rosa del desierto suffered an injury that required us to leave our Argentine registered bikes in Colombia and go to Spain for her medical treatment, but the process of obtaining this permission for our bikes to overstay their TVIP limits took almost a month. And, if the bikes you are intending to purchase were entered into Colombia on TVIPs, you might want to check the legally of purchasing the bikes.
There, I don't think I have overstepped my agreements with the HUBB not to discourage the sale of bikes in South America, but I cannot in good conscience let this post pass without my comment. You seem to be in a rush. My suggestion is to ask yourself Where am I? - and What am I doing? Please slow down you are in South America!

xfiltrate. eat , drink and make absolutely sure your insurance is valid.

ps I think there is thread on the HUBB set up to advise in which countries it is legal for tourists to purchase motor vehicles/bikes. Make sure you use the services of a local "hestor" ( one who is qualified to transfer titles ) for any title transfers.