In the table “Matched orders” you can find information about separate contracts with different Entry price, Liquidation price and margins.
The table “Open position” contains information about the trader's position where contracts are sum of contracts from “Matched orders” table and Position Margin is the sum of margins for all matched contracts, Entry price are the weighted average entry price among the contracts in the table “Matched orders” and Liquidation Price are the worst Liquidation Price among the contracts in the "Matched orders" tab.
For example, you placed 3 short orders each for 10 futures with leverage 100 on BTCUSD5 market at prices 47,385, 47,390 and 47,395. Liquidation prices will be 47,620, 47,625 and 47,630. But you will see only 47,620 in the "Open position" tab since this Liquidation price is worst (nearest to liquidation).