Budget allocation is not happening as per the proportion when there is only two distributions

Steps:
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1. Set the proportion for Budget Allocation for Google, Bing and Facebook as 0.20, 0.10 and 0.70 respectively.
2. Login to Reseller UI.
3. Create a merchant and save it.
4. Create an order and select all the three distributions.
5. Enter total monthly budget value as $100.
6. Budget will split between distributions based on the above proportions.
Google budget is 20, Bing budget is 10 and Facebook budget is 70.
7. Now, uncheck Bing and Facebook distributions. All the money should go into Google.
8. Now check the Bing distribution and verify Budget split.

Expected: Budget should split between Google and Bing as per the proportion value set in properties file. It should set 10 as Bing monthly budget.

Actual: Budget is splitting equally between distributions when there is only 2 enabled distributions.

See the attached screenshots.