Raiser's Edge allows manual addition of relationships between the same constituents, with the same relationship and reciprocal types; this is useful for when people move within the same organisation as employees but have different positions. However, Importomatic does not allow this, either letting you import with a non-constituent as the link, or overwriting what it assumes is duplications.

https://iom.uservoice.com/forums/18118-importomatic/suggestions/4960907-duplicate-search-matching-results-add-add-as-new suggested a similar solution - I recently had to import historical data for student association memberships linking alumni to the organisation (so you can view the relationship from either side) with each cohort being recorded separately as the council is dissolved and reelected (so someone in two consecutive terms would be recorded for example as 01/01/2018 - 31/12/2018 and 01/01/2019 - 31/12/2019) due to each council being a different entity. Some members also hold different positions, which need to be recorded accordingly (so if the above example also was the President in 2017, that would be another line with President as the position).

Because IOM doesn't allow this, it has to be done manually for anyone with more than one year's worth of service. Recording as grouped years (eg: 01/01/2017 - 31/12/19) is not an option due to people holding different posts in their time. IOM requires an option to always add as new, but also search for constituents rather than having the Add New functionality locked into non-constituents.