An entire institution is rarely justified by simply setting up an illusion for the average person to fall for. The US duopoly is a good example for this.
There is a very material incentive for the bourgeoisie to have precisely two parties alternating, that is, the importance of donors.
If the blue team were to lose only a small amount of donors, they would inevitably lose to the red team, and vice versa. If there were more major parties, losing donors could be a calculated decision to not alienate a part of the electorate, because the donations would go to one of the major parties. But in a duopoly situation, the donor’s money go straight to the other party, doubling the relative loss. On the contrary, a monopoly situation is not ideal because the importance of donors is diminished since the campaign is less important therefore money matters less.
This system therefore ensures maximum control over political parties by the bourgeoisie, because it optimises the bargain that donors have over party politicies
There is a cultural distinction that Matt Christman once made.
The capitalist state will do what it does your choice is to feel guilty about it (democrats) or proud to be an asshole (republican)
There are some differences in the tendencies for funding for various Bourgeoisie industries.
Democrats are more often supported by finance, tech, lawyers and the entertainment industry
Republicans are more often supported by Oil and small business tyrants
Otherwise, yes it is smart for any sufficiently large business to donate to both parties to keep the laws on their side.