The concept of ionic liquids (ILs) has evolved significantly over the past 40 years. The considerable amount of data obtained from the studies of compounds belonging to this group and the property models created from them have made it possible to verify early generalizations about ILs, that they were supposedly safe, non-toxic, thermally stable and "green" compounds, particularly in comparison to conventional organic solvents. When the potential problems of recycling and disposal of ILs were taken into account, as well as the effects of their introduction into the environment, the search for new sources of ILs ions, and safer methods of their synthesis became important. However, the possibility of almost free adaptation of ILs' structure to the desired properties (so-called "designability")including in the context of their toxicityand the related multiplicity of their potential applications in various industries remains an unquestionable advantage. As a result of the development of specific models on the basis of collected experimental data, methods based on machine learning are now becoming helpful in achieving favorable results and predicting the properties of designed ILs. However, the desired effect can be achieved not only by selecting the right combination of cation and anion or by slight structural modifications to one of the ions (e.g., altering the length of an alkyl chain), but also by creating entirely new ionic systems as a result of mixing 2 or more ILs. Such an approach offers an additional degree of freedom in the choice of cation and anion, does not require the design of a new synthesis process (as in the case of anion exchange or other structural modifications), and the resulting IL mixtures with potentially non-ideal characteristics can have new and unique properties that none of the constituent ionic liquids possess. To distinguish such systems from simple mixtures, the name double salt ionic liquids (DSILs) has been proposed for them. Analogous to deep eutectic solvents (DESs), numerous properties of DSILs result from chemical interactions between the constituent ions, and a change in the molar ratio of parent ILs can result in a significant change in the properties of a given system, which justifies investigating the physical, physicochemical and biological properties of various DSIL systems. Moreover, in some cases DSILs can become the basis for new DESs. In view of the advantages offered by the liquid, modular form of the active ingredient, including the ability to avoid the problems associated with the use of a solid form of the active ingredient (e.g., low bioavailability, polymorphism) and at the same time increase activity against the target organism through structural modifications or the use of an appropriate combination of ions, adherence to ILs (and, more recently, DESs ) concept is a legitimate strategy for designing new biologically active substances. In agrochemical treatments, it is popular to use more than one herbicide, since such a measure broadens the spectrum of action of the herbicide formulation, and can also counteract the acquisition of resistance by undesirable vegetation. It is also known that the transformation of the herbicide active ingredient into an IL may result in a significant increase in the biological activity of the new substance against weeds compared to reference formulations. At the same time, it should be emphasized that the observed increase in efficacy is mainly due to the favorable surface properties of the IL solution applied, which improves the penetration and action of the herbicide anion. Thus, it becomes reasonable to use a DSIL strategy and combine the surface-active cation with two or more active anions originating from known herbicides (e.g., 4-chloro-2methylphenoxyacetic acid (MCPA) or 3,6-dichloro-2-methoxybenzoic acid (dicamba)).