Fix paired techs following a754b1bad4. Patch by Imarok, fixes #4251, refs #3823.

This was SVN commit r18790.

binaries/data/mods/public/gui/session/selection_panels.js

@@ -745,9 +745,15 @@ g_SelectionPanels.Research = {
 			// Remove the techs we already have in ret (with the same name and techCostMultiplier)
 			let filteredTechs = state.production.technologies.filter(
 				tech => tech != null && !ret.some(
-					item => item.tech == tech && Object.keys(item.techCostMultiplier).every(
-						k => item.techCostMultiplier[k] == state.production.techCostMultiplier[k]
-			)));
+					item =>
+						(item.tech == tech ||
+							item.tech.pair &&
+							tech.pair &&
+							item.tech.bottom == tech.bottom &&
+							item.tech.top == tech.top) &&
+						Object.keys(item.techCostMultiplier).every(
+							k => item.techCostMultiplier[k] == state.production.techCostMultiplier[k])
+			));
 
 			if (filteredTechs.length + ret.length <= this.getMaxNumberOfItems() &&
 			    getNumberOfRightPanelButtons() <= this.getMaxNumberOfItems() * (filteredTechs.some(tech => !!tech.pair) ? 1 : 2))

binaries/data/mods/public/simulation/components/ProductionQueue.js

@@ -337,9 +337,13 @@ ProductionQueue.prototype.AddBatch = function(templateName, type, count, metadat
 			var template = cmpDataTemplateManager.GetTechnologyTemplate(templateName);
 			if (!template)
 				return;
-			if (this.GetTechnologiesList().indexOf(templateName) == -1)
+			if (!this.GetTechnologiesList().some(tech =>
+				tech &&
+					(tech == templateName ||
+						tech.pair &&
+						(tech.top == templateName || tech.bottom == templateName))))
 			{
-				warn("This entity cannot research " + JSON.stringify(templateName));
+				error("This entity cannot research " + templateName);
 				return;
 			}
 			var cmpPlayer = QueryOwnerInterface(this.entity);