It is Phaseolus vulgaris (common beans), which is the same as snap beans sold in the U.S.

Crossing can occur with other common beans (both bush & pole), including many soup or dry beans; and judging by your comments, this has happened to your Marconi Romanos.

If you took note of the original flower color, you might be able to purify the strain by roguing out the crosses... but if the crossing is widespread, this could take at least a couple of years. Since seed is still available, it might be best to just start over with fresh seed. The following two sources still carry it:

http://www.felcopruners.net/index.php/cPath/146_152

http://www.gourmetseed.com/bush_snap_bean_seed.0.html

Thanks that is what I thought. Some one tryed to convince me that beans can not cross, well I have the evidence. I just might order some more in the future, they did produce well, even in the years following The first one when they were pure. I may grow some of the seed again this year just to refresh my memory on how bad they are crossed.